Chesapeake Bay & Tributaries 2007 Year In Review
* For catch and release tips Click Here.
* For Real-time water information at selected points in the bay Click Here.
* For Real-time Conowingo Dam information Click Here.
Blue Crab Program
Trotliners had a positive start to the season in April. Unseasonably warm weather brought crabs out early in the shallow creeks and rivers. As the temperature cooled back to normal, crabbing slowed to a more traditional April pace. The remainder of the season proved to be above average for Trotliners. The season had a strong abundance of crabs with small fluctuations. The heavy rains that came in June wreaked havoc on all gear types. The influx of fresh water and the runoff muddied the water and scattered crabs. Many watermen commented that we had a hurricane without the winds, speaking about the heavy rains that came in June and July
Hard crab potters in the main stem of the Lower Bay had a good start in April helped along by the warm weather. After the strong start, most hard crab potters felt they had a slightly below average year due to a slightly lower abundance of crabs (Winter Dredge Survey) and a substantial increase in operating expenses. In the last year, the price of diesel fuel has increased, the cost of zincs has quadrupled, and razor clams are now very expensive and scarce. With this overhead, many watermen chose to leave their pots on land rather than operate in the red. The price of fuel also affected the frequency that pots were fished. Rather than crabbing every day watermen were leaving their gear to soak multiple days hoping for an increased catch. The fall produced a strong but short-lived female run. As quickly as it started, it was over.
Peeler potters had an average year with a fair amount of peelers harvested and the prices for soft crabs remained strong and stable with prices dropping and then rebounding. The expense of bait was not an issue, as peeler pots do not use bait. The watermen were impacted by the high cost of diesel fuel. The small window of opportunity for harvesting peelers before they shed makes the peeler crabber unable to let his pots soak for multiple days between fishing, as did the hard crab potters.
Scrapers had a below average year attributed mostly to the lack of grass. This impacted their catch because their harvest of peelers and soft crabs relies on harvesting crabs from grass beds while they take cover during the molting process.
Summer Migrant Species:
Weakfish, bluefish, Atlantic croaker, summer flounder and spot are all very popular migratory sport fish in Maryland. Fisheries Services has conducted summer pound net sampling since 1993 to track population trends in summer migrant species. DNR biologists examined fish captured in commercial pound nets from late May through September 2006. Data collected from this survey as well as commercial landings, estimates of recreational landings and knowledge of each species life history are used to evaluate and manage these species in Maryland. All of these species migrate in and out of Maryland waters and are managed on a regional basis, usually their entire range along the east coast of the Atlantic Ocean.
Atlantic croaker stocks have been high for several years. Maryland recreational anglers have landed between 825,578 and 2,674,800 fish from 1997 to 2005. All nine of those years were above the long-term average of 727,154, according to estimates by the National Marine Fisheries Service. The mean length of croaker examined from the pound net survey was 12.5 inches; this was fifth largest mean length of the 14-year time series. Croaker tend to have cyclic patterns of abundance with a few high years followed by a decline to a few low years followed by recovery. A recent stock assessment by the Atlantic States Marine Fisheries Commission (ASMFC) indicates the recent high abundance period has endured longer than those of the past. The ASMFC stock assessment estimated the mid-Atlantic population averaged 819.2 million fish from 1998 to 2002.
Weakfish have experienced a sharp decline in abundance coast wide. Recreational catch estimates by the NMFS for Maryland fell steadily from 475,348 fish in 2000 to 22,074 fish in 2005. The 2006 mean length for weakfish from the pound net survey was 11.4 inches, fifth lowest of the time series. Fish aged from the 2005 pound net survey were all 4 years of age or younger. These findings indicate weakfish migrating into Maryland’s waters do not appear to be surviving to older ages. The recent decline in abundance has occurred despite regulations designed to increase stocks. This may indicate an increase in natural mortality, through increased predation, loss of habitat, decrease in food availability and/or disease, but more research is needed before a cause can be determined.
Spot is a short-lived species with high growth rates. This type of fishery tends to be more variable from year to year, and more dependent upon recruitment of young of the year to adulthood. Juvenile indexes have been lower in recent years than the long-term average while recreational catch estimates have remained near “normal”. The 2005-year class was strong. The mean length of spot from the 2006 pound net survey was 7.75 inches. This is bellow average, but was driven down by the large number of small spot from the 2005-year class entering the fishery. These small spot not only give hope of more keeper spot next year, but also have and will provide quality forage for more popular sport fish such as weakfish, bluefish and striped bass.
Bluefish recreational harvest estimates were high through most of the 1980’s and have since been somewhat stable at a lower level. Mean length of bluefish from the pound net survey in 2006 was 12.25 inches, 7th highest of the 1993-2005 survey. Length distribution showed a modest shift back to smaller fish in 2006 after 2005’s increase in larger bluefish. Maryland’s portion of the Chesapeake Bay is primarily a nursery area for bluefish with a small and variable number of larger fish migrating here for anglers to catch. The latest coast wide stock assessment indicated the stock was not over fished and over fishing is not occurring.
Summer flounder mean lengths, from the pound net survey, increased to a time series high of 14.75 inches in 2005, but fell to a time series low of 11.4 inches in 2006. A sharp increase in young of the year flounder seamed to be the main reason for the lower mean, and is a good sign for the future. The recreational harvest estimate for 2005 increased over 2004, but still was the 6th lowest of the 1981-2005 time series at 85,212 fish. Flounder regulations are set to stay under a quota that varies from year to year due to stock status and a states harvest in previous years so comparing catch from one year to another is not necessarily indicative of changes in population or overall catch rates. The 2004 coast wide stock assessment indicated the stock was not overfished and overfishing is not occurring.
American Eel Project:
American eel is a catadramous species (lives and matures in fresh/estuarine water and migrates to spawn and die in the ocean) that is widely distributed from the southern tip of Greenland to Northeastern South America. Localized depletion and population declines have occurred in some areas, mainly in the Lake Ontario/ St. Lawrence River system, but also in neighboring Virginia. In recent years, coastwise eel scientists have been concerned about these declines and efforts to monitor and assess the stock have greatly increased. In late 2004 a formal citizen’s petition was issued to the United States Department of the Interior and Department of Commerce to declare the American eel an endangered species under the United States Endangered Species Act. The United States Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS) reviewed the petition and determined there was sufficient scientific information to warrant a formal status review of the species. In late 2005 and early 2006, the Services held several workshops with outside eel experts to review available information on potential threats and to discuss factors that have affected the population decline. The Services concluded their status review mid 2006 and will announce their formal ruling on American eel under the U.S. Endangered Species Act in early 2007.
Despite these declines, populations in Maryland have remained stable and have produced a quite viable commercial fishery. In the 1970’s Maryland’s commercial American eel fishery accounted for 8% of the entire Atlantic coast eel landings. This steadily increased to 10% in the 1980s to 29% in the 1990’s and since 1999 Maryland has accounted for more than 40% of coastwise American eel landings. Harvest of American eels occurs bayside in both the main stem and nearly all tributaries in Maryland’s tidal portion of the Chesapeake Bay.
DNR Fishery Service has an Eel Population Study that has been funded since 1997. DNR also participates in multi-state management of the American Eel through the Atlantic States Marine Fisheries Commission (ASMFC). Some of the main components of our Eel Population study include the young of year abundance survey that has been carried out in MD since 1997 and was then mandated by the ASMFC in 2001 for each state on the Atlantic coast, monitoring of the eel fishery through representative sub sampling of commercial catches, and a fishery independent survey in the Sassafras
Alosid Stock Assessment Program:
Adult American shad abundance in the Chesapeake Bay has declined over the last five years. American shad juvenile indices indicated poor spawning success, with the Potomac River as the exception. These factors together may indicate increased mortality on immature fish and poor survival of the young-of-the-year.
Adult hickory shad relative abundance indices in Deer Creek were stable but in the Nanticoke River indices decreased and with significant hatchery replenishment. Adult blueback and alewife herring abundance in the Nanticoke River have decreased significantly since 2000. Juvenile indices for both species have also decreased in recent years
Fish Passage Program:
In general, migratory fish numbers were again low in 2007. Conowingo dam passage numbers were down for the fourth straight year, only passing 25,464 American shad. Alewife and blueback herring counts were also below the average but hickory shad numbers remained steady or increased in some rivers.
It seems the 2007 calendar year has just ended and we are already preparing for 2008. As the Fish Passage Coordinator of Maryland, my job is to identify blockages which prevent fish from migrating up streams and rivers, and try to mitigate the blockage by either removing it, or installing a fish ladder. This past year was very successful for the Fish Passage Program. Working with various partners including the U.S. Fish & Wildlife Service, National Oceanic & Atmospheric Administration, the Chesapeake Bay Program, American Rivers, and many others – we successfully removed 3 dams across the State, opening habitat for fish and aquatic organisms, removing barriers to recreational boaters, and improving water quality. The Puckum Branch dam located on a tributary to the Marshyhope River was removed in January and reopened 4.5 miles of habitat to herring. The Raven Rock Dam (pictured below) near Hagerstown was removed in early October and reopened 2 miles of habitat for brook trout. The PPG dam, located on the Potomac River near Cumberland was removed in mid-October and opened 8.5 miles for American eel, and resident sport fish including walleye, muskellunge and bass. The removal also increased boating access for recreational use. We are already poised to remove 2-4 more dams in 2008 and provide passage for fish at several other sites.
Raven Rock Dam Removal in 2007, Before and After.
For more information regarding the Fish Passage Program, visit:
Striped Bass Program:
The spring, 2006 spawning stock survey indicated that there were 15 age-classes of striped bass present on the Potomac River and Upper Bay spawning grounds. These fish ranged in age from 2 to 16 year old fish.
The 2006 Juvenile Striped Bass Index was 4.3, which indicated a below average striped bass year-class in Maryland’s Chesapeake Bay. The index was less than the survey average of 11.9. This year’s results were comparable to results in 2002, when biologists observed similar draught conditions during the spring spawning period. Abundance indices for other anadromous species were also depressed in 2002 and 2006, supporting the theory that large-scale environmental factors such as low flow conditions may cause low recruitment to anadromous fish species in the Chesapeake Bay.
During the 2006 trophy season biologists intercepted 139 fishing trips, interviewed 344 anglers, and examined a total of 464 striped bass. The average total length of striped bass sampled was 923 mm TL (36.3 inches), and the average weight was 8.1 kg (21.7 lbs). The most commonly observed age group in the fishery was 10-year-old fish from the dominant 1996 year-class.
Average catch rate based on angler interviews was 2.6 fish per hour, which was a slight drop from catch rate in 2005 of 3.5 fish per hour. The difference in catch rates between years was not statistically significant. Many fishermen reported a drop in catches after May 10 due to warm weather and rapidly increasing water temperatures.
MD DNR biologists continue to tag and release striped bass as part of an interstate, coastal study. Over 1,500 tagged striped bass were released for growth and mortality studies. Anglers encountering a tagged striped bass are asked to help management efforts by reporting the capture of tagged fish. Just call the phone number printed on the tag.
MD DNR is continuing its voluntary angler survey on the Internet at http://www.dnr.state.md.us/fisheries/survey/sbsurveyintro.shtml, for recreational anglers to report their striped bass catch. This survey is designed to obtain important size data on harvested and released striped bass that is not otherwise available to the MD DNR.
Resident Species Project:
The Resident Species Project is charged with monitoring and assessing recreationally important tidal fish species that do not migrate out of state waters. These species include white perch, yellow perch, and channel catfish. Resident Species Project conducts fyke net surveys during the spring and a trawl survey during December – February. Results from our fieldwork and assessments indicate that channel catfish abundance has increased over the last few years. During 2007, the smaller channel catfish that were spawned over the last few years should be growing into respectable sizes. Populations are lower, however, when compared to all time high population levels during the late 1980’s and early 1990’s.
White perch fishers experienced a very good summer and fall during 2006. Our assessment during 2006 showed that populations were very healthy and fishing mortality was low. Recruitment (production of young white perch) has been generally very good since 1998; the exceptions would be somewhat poorer reproduction in 2003 and 2006. Yellow perch runs during the spring of 2006 were excellent. Populations were not forecasted to have tremendous expansion, rather, the successful spawning run underscores the fact that environmental variable are very important in determining availability to recreational anglers. Interestingly, there were more reports of summertime anglers having very good success in finding keeper yellow perch. What is in store for 2007 is not known. The warm winter water temperatures have kept yellow perch out of their typical deep-water habitat. Yellow perch are likely still in relatively shallow water, and without the schooling behavior usually seen in average or cold winters, predictions for the spring spawning run are difficult to make.
2007 Restoration and Enhancement Year in Review:
American shad and hickory shad restoration.
The project goal is reintroduction of self-sustaining populations of American shad and hickory shad in the watersheds of the Patuxent River, Choptank River and Nanticoke River. Historic DNR surveys indicated that shad species were severely depleted in these watersheds and lacked viable spawning populations. American shad restoration began in 1994 and hickory shad restoration began in 1996.
Marked hatchery fish are stocked as larvae and juveniles in the Patuxent River, Choptank River, Tuckahoe Creek, Marshyhope Creek and Nanticoke River. Nanticoke River restoration work is a cooperative program with Delaware Division of Fish and Wildlife. Mirant LLC also cooperates with DNR Fisheries Service Anadromous Restoration projects through their Chalk Point Aquaculture Center. The project is monitored through an adult electro fishing survey and juvenile seine survey. Since all hatchery fish are internally marked, we can identify whether a captured fish is hatchery origin or wild origin. This data is used to assess restoration progress.
Patuxent River American Shad.
American shad restoration is progressing as predicted in the three target tributaries. Restoration began in the Patuxent River in 1994. Hatchery origin juveniles were routinely captured during the early stages of the restoration effort but no wild juveniles were present in any collections from the river until 1998. Since then, wild juvenile abundance has generally increased over the years as hatchery fish return to spawn as adults. Early in the restoration project, most of the adults captured were wild origin and abundance was low. These fish were likely strays from other Bay tributaries. Hatchery fish stocked as juveniles began to return to the Patuxent River as adults in 1998. Hatchery fish dominated the adult population until 2003, when progeny of hatchery fish began to return to spawn in their native tributary as wild origin fish. The majority of spawning American shad adults in the Patuxent River is now wild origin, although the proportion is still variable. In 2006, a slight resurgence in hatchery fish contribution was observed. This was most likely due to the additional stocking of “early” juveniles (30 days age), beginning in 2002. In the early years of the restoration project, only larvae and “late” juveniles (75 days age) were stocked. After monitoring the composition of returning adults, we discovered that fish stocked as late juveniles did not return to the stocking river upon reaching maturity even though fish stocked as larvae did return. It was hypothesized that these late juvenile fish were stocked at an age that prevented proper imprinting to the stocking tributary. We also observed that larval survival was widely variable but once fish reached juvenile size, survival rates stabilized. In essence, once a shad juvenile reaches a certain size, mortality rates are stable until the fish migrate out of the natal rivers. The project stocked fish at various ages until it was determined that once fish reached approximately 25 days age, survival was stable and there was no real stock enhancement advantage to culture a juvenile to a larger size. Culture of these early juveniles costs less money and resources than late juvenile culture and we are able to rear many more fish for stocking. Theoretically, fish stocked at a younger age should be more likely to imprint to the stocking tributary and this was documented in 2006. Once these early juveniles began to show up in the adult population, we predicted that the hatchery contribution would remain high for several years. In 2007, hatchery contribution was elevated as expected. Large numbers of these early juvenile-stocked fish are present in 2007 adult collections. Fish stocked at this life stage are now dominating the hatchery-stocked component and impact the wild proportion due to their higher survival rate than either larval-stocked or wild-origin fish.
American shad catch and release fishing should be excellent this May in the Patuxent River based on previous stocking and monitoring data. The highest concentration of American shad should occur from Queen Anne Bridge down to Wayson’s Corner.
Choptank River and Marshyhope Creek American Shad.
There were relatively few adult American shad present in the Choptank River and Marshyhope Creek in 2007. American shad restoration expanded to the Choptank River in 1996 and to Marshyhope Creek in 2000.
Intensive American shad stocking in the Choptank watershed did not begin until 2002 so it might be a few more years until adults return to spawn in large numbers. We anticipate an increase in Choptank River American shad returns in 2008 and 2009. We encountered few American shad adults in 2007 Choptank River sampling. In addition to low brood stock abundance, sampling efficiency might influence data collection. We do not feel that our electrofishing gear adequately samples downriver, deep-water spawning habitat. As more adults recruit to the spawning stock, they should appear in upriver sample sites. We also presume that stocking levels have not been high enough in previous years to affect this large tributary. The project has made an effort to increase stocking numbers in this river over the last several years and this should result in increasing numbers of hatchery origin adults.
Marshyhope Creek restoration only began in 2000 and it is too early to accurately assess the progress at this time. American shad adults and juveniles of both hatchery and wild origin were captured in 2007.
Restoration in these rivers is progressing in a manner similar to that of the Patuxent River. Excellent American shad larval survival and high juvenile abundance documented in 2002 and 2003 should result in large numbers of returning adults beginning in 2008 and continuing into 2009.
Catch and Release fishing for American shad might yield a few strikes in 2008 on both the Choptank River and Marshyhope Creek. Choptank River anglers should concentrate their efforts from the 313 Bridge and downstream. Marshyhope Creek is likely to produce some fish from just above Federalsburg to several miles downstream.
Hickory shad reach maturity at a younger age than American shad. Since they return to spawn in three to four years, hatchery reintroduction can be successful in a shorter time frame. For example, Patuxent River restoration began in 1996. Hatchery fish dominated the spawning population by 2001. Sampling conducted in 2004 indicated that most adult hickory shad on the spawning grounds were wild origin. Both adult and juvenile Patuxent River surveys indicate abundant hickory shad populations over the last few years and we predict that this trend will continue. Adult populations were comprised of mostly wild origin fish from 2004 through 2007 (>80%). Choptank River and Nanticoke River surveys also indicate similar trends as catches have been increasing in recent years.
Hickory shad Patuxent River.
Analyses of 2007 samples indicate hatchery fish comprised only 11% of the adult population. Hatchery contribution to the adult stock have been below 20% since 2004 suggesting a self-sustaining stock, therefore we have decided to discontinue stocking hickory shad in the Patuxent River and redirect those efforts to the Choptank River and the Marshyhope Creek in 2008.
The Patuxent River should provide many opportunities for hickory shad catch and release fishing in 2008. Sampling for adults in 2007 indicated a large population of adult hickory shad on the spawning grounds. Hickory shad begin to arrive at the end of March, dependent on water temperature. Peak spawning temperature for hickory shad is 58-62?F. The highest concentration of shad should begin about a mile or so below Queen Anne Bridge and continue above the bridge to Route 50. Hickory shad will tend to congregate farther upstream than American shad. While there is some access by land, a small boat, kayak or canoe would enable the angler to cover more water.
Hickory shad Choptank River.
The Choptank River is beginning to showing signs of restoration. Adult recaptures from 2004-2007 indicate hatchery contribution below 30%. In 2007, hatchery contribution to the adult population was only 19%. We predict that this trend will continue based on experience gained in the Patuxent River. We anticipate an increase in hickory shad returns in 2008 and 2009. Stocking will continue in 2008.
Choptank River shad fishing should be excellent in 2008. Hickory shad can be caught in the main stem Choptank from Red Bridges down to Greensboro. Tuckahoe Creek has produced some decent hickory shad fishing in the past, principally below Crouse Mill Dam. However, anglers have reported reduced success there over the last few years.
Hickory shad Nanticoke River.
The Nanticoke River currently has a remnant wild spawning population of hickory shad. Stocked fish are also beginning to return to this watershed. The combination of the remnant wild population and hatchery origin adults should provide some angling opportunities in 2008. Most of the shad habitat in the main stem Nanticoke exists in Delaware. The best opportunity for Maryland anglers to catch shad in this watershed is Marshyhope Creek. Migrating shad will be concentrated in the area from Federalsburg up to the Maryland-Delaware line. As in other tributaries, hickory shad will occur farther upriver than American shad. Hickory shad will likely be more abundant than American shad in this tributary since restoration stocking began only a few years ago.
Warm Water Hatcheries
Our warm water hatcheries culture fish species for many Fisheries Service projects including tidal bass enhancement, corrective stocking in state lakes and rivers, farm pond stocking and the fishing rodeo program. Cultured species include largemouth bass, small mouth bass, hybrid sunfish, redear sunfish, yellow perch, bluegill, walleye, golden shiners and striped bass. The facilities are located at Unicorn Lake Fish Hatchery on the Eastern Shore and Cedarville Hatchery in Southern Maryland.
In addition to warm water species culture, these hatcheries perform all anadromous (migratory) species culture for restoration projects. They also culture rainbow trout for regional put and take stocking projects, alleviating pressure on our traditional coldwater culture facilities. The diverse nature of culture responsibilities for the warm water hatcheries results in complex utilization of staff and resources. It is unusual to produce warm water, cool water, cold water and anadromous species all at a single facility.
Current research at these hatcheries is focusing on new marking techniques to identify hatchery fish in the wild. A new technique uses a flourochrome compound called calcein to mark hatchery fish. Fish are immersed in a calcein solution, which chemically binds to all the bony or calcified structures (fin rays, vertebrae, scale margins, otoliths). When excited by blue light of a specific wavelength, the marked structures will fluoresce, or glow under the light (Se-mark™, Western Chemical, and Ferndale, Washington). This provides biologists with a non-lethal method to identify a captured fish as hatchery origin. This information is useful in population assessment and monitoring survival and movement.
New marking strategies utilizing oxytetracycline (OTC) immersion are being explored for use in tidal largemouth bass research. This chemical also marks the bony structures of fish. Investigation into marking early versus later life stages will help to develop the most effective stocking strategies for this species.
Warm water hatcheries also continue to work closely with Fisheries Service Regional Operations investigating the utility of tagging bass with coded wire tags (CWT). These one-millimeter long tags are implanted in the musculature of juvenile fish and allow future identification of hatchery-origin fish. CWT is positively identifiable and capture data can be used to calculate survival and abundance validate ageing techniques or evaluate experimental marking strategies for retention.
We also cooperate with U.S. Fish & Wildlife Service (USFWS) and U.S. Food & Drug Administration to conduct aquaculture drug research. Data generated by DNR is used to evaluate the safety and efficacy of new therapeutants proposed for use in aquaculture.
Atlantic sturgeon restoration.
Fisheries Service has teamed up with USFWS, Mirant LLC and University of Maryland to restore spawning populations of Atlantic sturgeon to Maryland’s Chesapeake Bay tributaries. This prehistoric fish historically spawned in most of Maryland’s larger tidal rivers. The Atlantic sturgeon is a species like no other in the Chesapeake Bay. Sturgeon originated 120 million years ago and continue to exist today. They can live more than 60 years and the largest Atlantic sturgeon specimen ever recorded reached 14 feet and 811 pounds. Virtually the entire Maryland spawning stock was depleted during a period of over-fishing in the late 1800s and it has not recovered to this day. There is still a small spawning population in Virginia’s James River. We are attempting to culture a captive brood stock, which will be used to produce hatchery origin sturgeon. Hatchery-origin larvae and juveniles should return to the stocked tributaries to spawn. The captive brood fish originate as Chesapeake Bay migrants. These fish are foraging in Maryland waters but their origin is likely from other systems such as the Delaware River, James River or Hudson River. Genetic studies conducted for DNR by the USFWS Northeast Fishery Center in Lamar, Pennsylvania (USFWS NFC) indicate that sturgeon captured in the Chesapeake Bay are likely from other systems such as the James River and the Hudson River. These wild migrants are collected from Maryland waters and brought to various culture facilities. Most of these migrant fish are age three to six years. Female Atlantic sturgeon don’t reach maturity for 15-20 years in the Chesapeake region. Therefore, these fish will be cultured for many years before they are old enough to spawn in the hatchery.
While we are culturing the brood stock to maturity, we are busy acquiring the tools, technology and methodology that will be required for such an ambitious undertaking:
- We are utilizing microsatellite DNA analysis to determine relatedness and origin of the brood stock. This information will be used to create a brood stock management plan to insure that we are producing progeny that will be genetically fit. This work is a cooperative effort with the (USFWS-NFC).
- We are using laparoscopic surgery to assess sexual maturity. In this process, an endoscope is inserted through a small incision in the body cavity. This minimally invasive procedure allows us to monitor the progress of sexual maturity without imparting undue stress to the animal.
- We are experimenting with different techniques to train wild-caught sturgeon to eat commercial fish diets in the hatchery and investigating various nutrient strategies for larval and juvenile sturgeon. The University of Maryland Aquatic and Restoration Ecology Laboratory (AREL) performs this research at the Horn Point campus in Cambridge, Maryland.
- We are investigating whether cryogenically preserved sturgeon sperm can be used to successfully fertilize eggs. Frozen sperm could be stored indefinitely and a genetically diverse collection could be maintained on site at the culture facilities. If this technique can be perfected, it will provide greater flexibility in population restoration, culture and spawning work.
- We are developing tagging or marking techniques for larval and juvenile hatchery-origin Atlantic sturgeon.
In April 2007, a Maryland waterman reported the capture of a large Atlantic sturgeon to the Maryland Sturgeon Reward Program. DNR and the USFWS Maryland Fishery Resources Office (USFWS-MFRO) jointly operate this cooperative program. A monetary reward is offered for the report and delivery of live Atlantic sturgeon. The Maryland Sturgeon Reward Program is used to monitor sturgeon populations in Maryland’s Chesapeake Bay. Suitable captures are also used to supplement the Maryland Atlantic sturgeon restoration project.
The large sturgeon was captured near Tilghman Island. The fish was transported to AREL. All potential captive brood fish are brought to AREL for training to commercial diets since wild-caught fish do not readily accept food in captivity. Subsequent surgical assessment indicated that this fish was a ripe female that measured 7½ feet and weighed 171 pounds. No ripe female has been reported during the eleven years of the reward program and in fact, no ripe female has been documented in Maryland or nearby regional waters since 1972. Preliminary genetic analysis indicated the fish to be either Hudson River or Delaware River origin. Upon discovery of the reproductive status, plans were formulated to attempt spawning. Successful spawning and culture would provide suitable larvae and juveniles that could be stocked and used to evaluate survival, migration, habitat suitability and habitat preference. The fish was monitored periodically to assess the maturation progress of the eggs. When biopsy assessment indicated that the eggs were sufficiently mature, biologists injected the female with spawning hormones. Eggs were then surgically removed from the female and fertilized with cryogenically frozen sperm. The egg quality appeared poor at the time of surgery and later assessment confirmed that fertilization and viability was zero.
Biologists are currently assessing the procedure in order to determine the reason that the eggs were not of good quality. Very few Atlantic sturgeon have been successfully spawned in captivity and most of the success has been obtained from fish taken either directly from the spawning tributaries or held in captivity for several years. The Tilghman Island female was captured in the main stem Bay and held captive for several months prior to spawning, further complicating the process. Nevertheless, a great deal of knowledge was acquired during the procedure and we feel confident that captive fish can be successfully spawned. The female recovered well from surgery and is currently maintained at AREL. She will be held in captivity until she produces eggs again. At that time, another spawn will be attempted.
Cryogenic preservation work is conducted in partnership with USFWS Warm Springs Fish Technology Center (Warm Springs, Georgia) and USFWS-NFC. We will continue to refine this technique in future years. The goal of the research is to refine cryopreservation techniques and create an archive of genetic material that will be redundantly stored at USFWS-Warm Springs, USFWS-NFC and Maryland DNR’s Manning State Fish Hatchery.
We conducted experimental trials in 2007 at Manning State Fish Hatchery to refine Atlantic sturgeon culture procedures. Yolk-sac larvae were obtained from a Canadian source (Acadian Sturgeon and Caviar Company) for this purpose. One goal was to identify potential stumbling blocks to successful early life stage culture at our facility. The other goal was to construct recirculating aquaculture systems so we will have the ability to culture fish throughout the year under optimal conditions. Manning Hatchery was originally designed as a flow-through facility so it is a major departure to transition into recirculating systems. Maintaining water quality is a challenge in this type of culture and the Canadian source fish allow us to troubleshoot systems and techniques before we have the ecologically valuable larvae and juveniles we hope to produce from our captive brood stock. Survival of the Canadian fish was high and we feel we now have the ability to successfully culture larvae at our facility. Operation, improvement and refinement of recirculating systems at Manning will continue to evolve.
Atlantic sturgeon are believed to imprint on their natal rivers, allowing them to return to spawn upon maturity. The mechanism and timing of this homing behavior, or fidelity, are not fully understood at this time. It is critical that any fish stocked as larvae or juveniles will imprint to the target tributary, so that they may successfully return to spawn. One way to improve the chances that appropriate imprinting will occur is to culture larvae and juveniles in water from the target tributary. Development of streamside culture techniques could insure that any fish stocked will imprint to their river of “origin” and return there to spawn when they reach maturity. This technique is especially important since Atlantic sturgeon take fifteen to twenty years to mature. This extended maturity schedule means that any imprinting failure will not be detected for up to two decades. In order to address this issue, we conducted an experimental trial with the Mirant Potomac River Generating Station to investigate the potential for streamside Atlantic sturgeon culture. Mirant contributed significant financial resources, construction manpower and cooperation to implement the culture operation. This power generation plant is located on the Potomac River in Alexandria, Virginia. The Potomac River is a likely candidate as a target tributary for Atlantic sturgeon restoration so this partnership was a good fit. The results of the trial this year indicate that there is real potential for successful streamside Atlantic sturgeon culture in the Chesapeake Bay.
Several Atlantic sturgeon marking techniques were evaluated. Technologies investigated include radio frequency identification tags (RFID) (Biomark Inc., Boise, Idaho), immersion in chemicals that stain bony and cartilaginous tissues and implantation of silicon-based elastomeric liquids (Northwest Marine Technologies Inc., Shaw Island, Washington).
RFID tags are commonly used in fisheries research. The limiting factor to this technology is that only sturgeon longer than approximately six inches in length can be implanted. Calcium-staining is an excellent methodology to batch mark large numbers of larval fish. We do not know how long these marks can be identified using non-lethal assessment techniques. Chemical marking research will continue in future years. Elastomers are injected just beneath the skin. The liquid cures to a solid that is visible beneath translucent tissues. In 2007, Canadian sturgeon held at Manning Hatchery were evaluated for elastomer mark retention. After one year, marks were still visible using a Se-mark™ detector indicating the potential for future use. Future work will investigate using genetic analysis to identify markers that are specific to hatchery fish.
The Fisheries Service Atlantic Sturgeon Restoration Project is a great example of the importance of cooperative partnership efforts. This project utilizes the resources and expertise of the federal government, state government, university researchers and commercial enterprises to reach a common and mutually beneficial goal. Restoration of this historically and ecologically important species cannot occur without the contribution of all the partners. Funding is now the biggest obstacle to Atlantic sturgeon restoration in Maryland. It is difficult to obtain continuous funding over several decades for a single species. Our focus in the near future will be to secure long-term funding in order to continue this important work.
Fish Habitat Project:
Fisheries management is increasingly using biological reference points (BRPs) to determine how many fish can be safely harvested from a stock. . The primary objective of Fish Habitat Project is to evaluate the concept of using impervious surface reference points (ISRPs) as a similar tool for fish habitat management.
The development of ISRPs involves determining functional relationships between impervious cover and water quality (primarily dissolved oxygen) or a species population response (abundance, distribution, mortality, recruitment success, growth, etc). Dissolved oxygen is an ideal response variable because fish require well-oxygenated water and because it can provide insight into both the metabolic and pollution status of a water body.
Land is converted to impervious surface (paved surfaces, buildings, and compacted soils) as human population grows. By most measures, human impacts have grown faster than the population. A variety of studies have documented deterioration of freshwater aquatic ecosystems as impervious surface occupied more than ten percent of watershed area. Impervious surface increases runoff volume and intensity in streams, leading to physical instability, and increased erosion and sedimentation. This runoff, warmer than water draining forests or other porous lands, becomes a source of thermal pollution. Impervious surface runoff transports a wide variety of excess nutrients that contribute to algae blooms, hypoxia, and anoxia. A strong relationship between impervious surface and dissolved oxygen was found during 2003-2007 in the Chesapeake Bay tributaries that were sampled by this project.
Habitat issues associated with impervious surface are not limited to just dissolved oxygen. It is recognized that development per se, urbanization and industrialization, contribute significantly to contaminant loads, eutrophication, and physical degradation of coastal areas. Because of excessive concentrations of PCBs and organochlorine pesticides (Maryland Department of Environment, www.mde.state.md.us), consumption advisories have been issued for organochlorine compounds in white perch (Morone americana) in most suburbanized estuaries. Disruption of reproduction could be caused by these anthropogenic chemicals or persistent hypoxic oxygen conditions threatening a wide variety of finfish.
Beginning in 2003, Maryland Department of Natural Resources, Fisheries Service initiated studies examining impacts of land development on fisheries in the Bay. These studies indicated that when impervious surface (rooftops, roads, sidewalks, parking lots and compacted soils covers 10% or more fish habitat is significantly impaired and fish populations decline. Dissolved oxygen levels bottom habitats fall directly with the amount of impervious surface in a watershed. The effect is a direct reduction of fish and crab abundance in the bottom to mid-water depths because the habitat is no longer suitable.
Starting in March 2007 the Fish Habitat Project, along with citizen volunteers, set fish traps and deployed drift nets in the flowing freshwater portion of selected tributaries of the Bush River to document the presence of spawning anadromous fish. Overlapping with the tail-end of this activity in March and continuing into April, project personnel pulled plankton nets in the tidal portions of the Bush and Corsica rivers and Langford Creek to document the presence or absence of larval anadromous fish. In May, small fine-mesh “fry” seines were used to capture juvenile anadromous fish in these watersheds.
During summer 2007 (July – September), The North East River was sampled in the upper Bay, the Bush, Corsica, Langford, Wye and Tred Avon rivers were sampled in the mid-Bay region, while Mattawoman and Piscataway rivers were sampled in the Potomac River. Impervious cover in these systems spanned 0.7% - 16.7% of watershed area. Four evenly spaced sample sites were sampled once a visit and there were two visits a month during July-September.
Trawling and seining were used to sample fish populations. Gear specifications and techniques were selected to be compatible with other Fisheries Service surveys. A 16 ft semi-balloon otter trawl was used to sample mid-channel bottom habitat. A 100 ft by 4 ft beach seine, the standard gear for Bay inshore fish surveys was used to sample inshore habitats. All fish captured were identified to species and counted. Water quality parameters were recorded at all sites.
Overall sampling in 2007 showed anadromous fish spawning (white and yellow perch, and herring) was more likely to occur at sites in the low development portion of the watershed (APG) than in the highly developed portion.
Water quality in the areas sampled in 2007 appeared to be adequate to support fish according to their habitat requirements. While every river sampled had some violations, the only river that showed signs of impairment was the Corsica River where dissolved oxygen frequently was measured below the 5.0 mg/L criteria. This is similar to what we observed in the Corsica in past years. The Corsica received a significant organic load for an undetermined amount of time, from a failing wastewater treatment plant. This load is likely contributing to the low oxygen conditions. The Corsica is the subject of a state-guided restoration effort, where best management practices will be applied to land in the watershed. We intend to continue to monitor the Corsica to determine if we can see measurable results in habitat improvement.
We will continue in 2008 to sample these tidal tributaries to further explore the effects of impervious surface on tidal-fresh habitats and develop a better understanding of the processes that impact the fish community in these areas.
Fish Health Program:
The Fish and Wildlife Health Program (FWHP) continued its study of Mycobacteriosis, a bacterial disease that has been present in the striped bass population since at least the mid 1980s. Prevalence of this disease in fish collected from pound nets has increased from 25% in 1998 to 60% in 2006, but has leveled off since 2004. Data analysis of fish collected in 2007 is underway. This disease is first evident in age-1 striped bass and increases in both male and female fish with age until at least age-6. Lesions caused by this disease are most evident on 4 to 7 year old fish (approximately 18-28”). Mycobacteriosis is not limited to the Chesapeake Bay, although the prevalence of this disease (and external lesions in general) is significantly lower in the migratory spawning stock.
In 2007 the Maryland Department of Natural Resources (MD DNR) and the Virginia Institute of Marine Science (VIMS) began a cooperative tagging study to estimate the impact of Mycobacteriosis on the striped bass population in both the upper and lower reaches of the Chesapeake Bay. VIMS initiated this tagging study in 2005 to track the progress of the disease in the Rappahannock River, Virginia. During the spring and fall of 2007 MD DNR and VIMS tagged and released more than 3,000 striped bass with a unique bright green colored tag. The bright green tags are marked with either “VIMS” or “MD DNR” and include a toll free number (1-866-845-3379) to report the fish. If you catch a striped bass with a green MD DNR or VIMS tag hold onto the fish and report it immediately so that fish health biologists can arrange pickup and analyze the skin and internal organs for disease.
Above are Striped Bass with tags.
For best results, it is important that fish are reported promptly after capture, kept intact (DO NOT FILET) and chilled with ice (DO NOT FREEZE). A $20 reward is available for each fish that is picked up by DNR biologists. If you choose not to hold the fish, we ask that you clip the tag off the fish close to the body and call the number listed. A $5 reward will be paid for the return of each green tag and information on when and where the fish was caught. This study will continue through at least 2009.
Handling and consumption of diseased fish is a continued concern for both anglers and commercial watermen. The bacteria that cause this disease in fish do not pose an unusual danger to fishermen, but it is possible to contract an infection by handling sick fish, particularly if you have open cuts on your hands or if a fish spine penetrates your skin. Therefore, we recommend simple precautions like handling fish with gloves and washing hands frequently. Having a bottle of the waterless anti-bacterial hand wash on hand is a good idea. Although the Department of Health and Mental Hygiene has found no association between consumption of diseased fish and human mycobacterial illness, MD DNR recommends that anglers avoid consuming any fish with visible sores.
Click here for information concerning harmful algae blooms
Click here to view recent bay satellite images at mddnr.chesapeakebay.net/NASAimagery/EyesInTheSky.cfm
The link below has some very valuable
information for Chesapeake Bay Anglers. DNR's "Eyes on the Bay" website
has data coming in from remote sensing stations in the Chesapeake Bay and
tributaries. It is well worth checking this out. Click on the map below.
Service is pleased to have you visit. We want to make this
site as user friendly as possible, if you have any suggestions, please
mail them to