Chesapeake Bay & Tributaries 2008 Year In Review
Striped Bass Program
The spring, 2008 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 18 years old. Age 4 (2004 year-class) and age 5 (2003 year-class) male striped bass were the most abundant component of the male striped bass spawning stock. Age 12 (1996 year-class) and age 15+ (1993 year-class) females were the major contributors to 2008 total female abundance. Age 8 and older females comprised 95% of the female spawning stock in 2008.
The 2008 striped bass juvenile index, a measure of striped bass spawning success in Chesapeake Bay, is 3.2, below the long-term average of 11.7. During the survey DNR biologists collected 422 young-of-year (YOY) striped bass.
Healthy striped bass populations are known for such highly variable spawning success. This is just the third time in the past decade that striped bass reproduction in Maryland’s Chesapeake Bay has been below average. Two of the most successful spawning years ever documented (2001 and 2003) also occurred during this past decade. Typically, several years of average reproduction are interspersed with occasional large and small year-classes.
Poor reproduction was also observed for other spring-spawning species such as white perch and American shad, leading biologists to suspect that large-scale environmental factors were responsible. Heavy rains in early May resulted in decreased water temperatures on major striped bass spawning grounds. The spring water temperatures fell below levels known to be lethally cold to striped bass eggs and larvae, and survival of these sensitive life stages is a major determinant of spawning success. The underlying spawning stock is still healthy and is watched closely by DNR biologists and monitored in partnership with other coastal states through the Atlantic State's Marine Fisheries Commission.
During the 2008 trophy season, biologists intercepted 271 fishing trips, interviewed 329 anglers, and examined a total of 200 striped bass. The average total length of striped bass sampled was 920 mm TL (36.2 inches), and the average weight was 7.8 kg (17.2 lbs). Most fish sampled from the trophy fishery were between nine and twelve years old. The 1996 year-class (age 12) and 1997 year-class (age 11), were the most frequently observed year-classes, constituting 45.6% of the sampled harvest. Average catch rate based on angler interviews was 0.3 fish per hour.
MD DNR biologists continue to tag and release striped bass as part of an interstate, coastal study. Approximately 1,661 striped bass were tagged and 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 by calling the phone number printed on the tag.
MD DNR, Fisheries Service is continuing its voluntary angler survey on the Internet (www.dnr.state.md.us/fisheries/survey/vasurvey.html) 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
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 cooperating watermen, from late May through September 2008. 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 2007. All eleven of those years were above the long-term average of 744,187 according to estimates by the National Marine Fisheries Service. The mean length of croaker examined from the pound net survey in 2008 was 11.75 inches; this was ninth highest mean length of the 16-year time series. Fish aged from the 2007 survey ranged from 1 – 12 years old. The croaker population tends to have cyclic patterns of abundance, with a several high years followed by a decline to several 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 493 fish in 2006, and increased in 2007 to 11,910 weakfish, but was still well bellow the long term mean of 338,280 fish. The 2008 mean length for weakfish from the pound net survey was 10.8 inches, the third lowest of the time series. Fish aged from the 2007 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, or that older fish are not migrating into Maryland. 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 2007 and 2008 year classes appeared to be relatively strong. The mean length of spot from the 2008 pound net survey was 7.8 inches. This is slightly bellow average, and the percent of spot over 10 inches in the pound net samples was very low (less than one percent). The increase in juvenile 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 2008 was 10.2 inches, 2nd lowest of the 1993-2008 survey. This was a decrease from the above average mean length of 12.5 inches in 2007. 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 length from the pound net survey was 13.7 inches in 2008, a little above average for the 16 year survey. More large flounder were measured in 2008 compared to 2007. The recreational harvest estimate for 2007 of 157,360 flounder increased over 2006, but was still bellow the 1981-2007 time series mean of 232,916 fish. I would expect similar or possibly higher landings for 2008, due to the presence of larger fish in the 2008 pound net survey. 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 catches rates. The 2006 coast wide stock assessment indicated the stock was not over fished but over fishing is occurring. This is the reason higher size limits and lower creel limits have been established, to reduce the number of fish being removed from the population.
Black drum, red drum, Spanish mackerel and spotted sea trout are also examined by the survey. Spanish mackerel is the only one of these species encountered on somewhat regular bases in the southern portion Maryland’s Chesapeake Bay, because it prefers higher salinities. Maryland tends to be on the northern end of the other three species range, but they are generally available to anglers here in the summer months.
American Shad and Hickory Shad Restoration
The project goal is the creation of self-sustaining populations of American shad and hickory shad through introduction of hatchery-produced larvae and juveniles. Target watersheds include the Patuxent River, Choptank River and Nanticoke River. DNR surveys indicated severely depleted shad stocks in these watersheds and lack of viable spawning populations. DNR’s shad restoration project is a collaborative effort. Nanticoke River restoration work is a cooperative program with Delaware Division of Fish and Wildlife. Mirant LLC also cooperates with DNR restoration projects through their Chalk Point Aquaculture Center.
Patuxent River American Shad
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. Adult composition has also shifted toward wild fish. In 2008, hatchery fish represented only 33% of the recaptured adults. Catch and release anglers might catch an American shad or two along the two-mile stretch below Queen Anne Bridge. If you are traveling by boat, be aware of the tide. Boating traffic is only advisable on a flooding or high tide.
Choptank River and Marshyhope Creek American Shad
There were relatively few adult American shad present in the Choptank River in 2008. Even though the river has been stocked since 1996 at a low level, intensive American shad stocking did not commence until 2002. Therefore, it might be a few more years until adults return to spawn in large numbers.
Marshyhope Creek restoration began in 2000 and it is too early to accurately assess the progress at this time. In 2008, 15% of recaptured American shad adults were of hatchery origin. Excellent American shad larval survival and high juvenile abundance documented in 2002 and 2003 should result in large numbers of returning adults beginning in 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 Greensboro boat ramp downstream to Depue Landing Road. Marshyhope Creek is likely to produce some fish from just above Federalsburg to several miles downstream.
Hickory Shad Patuxent River
Analyses of 2008 samples indicate that hatchery fish comprised only 19% of the adult population. Hatchery contribution to the adult stock has been below 20% since 2004. Since the population seems to be stable and self-sustaining at this time, we have decided to discontinue stocking hickory shad in the Patuxent River. We will continue to monitor the adult population to assess natural reproduction.
The Patuxent River should provide many opportunities for hickory shad catch and release fishing in 2009. Sampling for adults in 2008 indicated a large population of adult hickory shad. Hickory shad should begin to arrive in early March and will peak in early to mid-April. The highest concentration of shad should begin about a mile or so below Queen Anne Bridge and continue above the bridge to Route 50. 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 indicates a positive restoration response. Adult captures from 2004-2007 indicate hatchery contribution below 30%. In 2008, hatchery contribution to the adult population was 35%. This slight increase is due to stocking large numbers of early juveniles in 2002. We predict that the proportion of hatchery fish will continue to decline, based on experience gained in the Patuxent River. Choptank River stocking will continue in 2009.
Choptank River shad fishing should be excellent in 2009. Hickory shad are normally caught in the main stem 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 several 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. In 2008, data from the adult electro fishing survey determined that hatchery contribution to the adult population was 25%. This is an increase from 13% in 2007. The combination of the remnant wild population and hatchery origin adults should provide some angling opportunities in 2009. Most of the hickory shad habitat in the main stem Nanticoke exists in Delaware. Marshyhope Creek is the best opportunity for Maryland anglers to catch hickory shad in this watershed. Migrating shad will be concentrated in the area from Federalsburg up to the Maryland-Delaware line.
Atlantic Sturgeon Restoration
Fisheries Service has teamed up with USFWS, Mirant LLC and University of Maryland to restore Atlantic sturgeon spawning populations to Maryland tributaries. This prehistoric fish historically spawned in most of Maryland’s large tidal rivers. Sturgeon originated 120 million years ago. They can live more than 60 years and the largest Atlantic sturgeon specimen ever recorded reached 14 feet and 811 pounds.
DNR cultures a captive brood stock, which will be used to produce hatchery origin larvae and juveniles for restoration stocking. The captive brood fish originate as Chesapeake Bay migrant juveniles. These fish forage in Maryland waters but genetic analysis indicates that they originate from other systems such as the Delaware River, James River or Hudson River. Female Atlantic sturgeon do not 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 culture the brood stock to maturity, we are busy acquiring the tools, technology and methodology that will be required for such an ambitious undertaking.
Maryland DNR and the USFWS Maryland Fishery Resources Office (USFWS-MFRO) jointly operate the Maryland Sturgeon Reward Program. A monetary reward is offered for the report and delivery of live Atlantic sturgeon. The reward program is used to monitor sturgeon populations in Maryland. Suitable captures are incorporated into the captive brood population.
Cryogenic gamete preservation research is conducted in partnership with University of Maryland Crane Aquaculture Facility, USFWS Warm Springs Fish Technology Center and USFWS-Northeast Fishery Center (USFWS-NFC). The goal of the research is to develop techniques for long-term storage of sturgeon sperm and to create an archive of genetic material that will be redundantly stored at USFWS-Warm Springs, USFWS-NFC and DNR’s Manning State Fish Hatchery. In July 2008, three Atlantic sturgeon males from Chalk Point Aquaculture Center were hormonally-induced to produce sperm. These samples were analyzed and preserved at UM-Crane Aquaculture Facility. Similar trials are planned for 2009.
Larval sturgeon culture trials continued in 2008 at Manning State Fish Hatchery, University of Maryland Aquaculture Restoration and Ecology (AREL) laboratory (Cambridge, MD), and Mirant Potomac River Generating Station (Alexandria, VA) to refine Atlantic sturgeon culture procedures. Yolk-sac larvae were obtained from the Acadian Sturgeon and Caviar Company (Saint John, NB, Canada) for this purpose. One goal was to identify potential stumbling blocks to successful early life stage culture at our facilities. The other goal was to construct effective recirculation and flow through aquaculture systems so we will have the ability to culture fish throughout the year under optimal conditions. 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. We feel we now have the ability to successfully culture larvae at all partner facilities.
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. 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 imprinting failure will not be detectable for many years due to the late maturity of Atlantic sturgeon. 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. The results of the trial this year indicate that there is real potential for successful streamside Atlantic sturgeon culture in the Chesapeake Bay. In 2008, several facility design changes greatly improved water quality. Mirant will provide up to $325,000 over the next five years to support Atlantic sturgeon restoration activities.
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 sturgeon must be six inches in length before they can be implanted. Calcium staining is an excellent methodology to batch mark large numbers of larval fish. We do not yet 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, sturgeon held at Manning Hatchery were evaluated for elastomer mark retention. After one year, marks were still visible using a Se-mark™ detector. 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.
Shad and Herring
American shad stocks after peaking around 2001 continue to decline to precariously low levels and is a result of ocean and Chesapeake Bay bycatch, predation and habitat loss. Monitoring efforts throughout the Bay have shown increased mortality rates and fewer older fish and this trend is observed in most east coast states. Atlantic States Marine Fisheries Commission (ASMFC) recently completed its American shad stock assessment and many of this reports conclusions are being addressed in an evolving Amendment.
Alewife and blueback herring, collectively known as river herring have also decreased in the past ten years and in Maryland are also at very low historic levels. Overfishing, predation, loss of habitat and ocean bycatch appear to be the causing the decline but ASMFC’s Amendment 2 will likely address these issues and serve as a proactive to enhance and protect remaining river herring stocks.
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 quality-sized channel catfish abundance has continued to increase. During 2009, the medium-sized channel catfish that were spawned over the last few years should be growing into respectable sizes. Populations have rebounded from low levels, but recruitment has been poor since 2006. In general, it takes channel catfish about 4 years to reach 16”.
White perch fishers experienced a very good summer and fall during 2008. White perch were last assessed during 2006. The assessment showed that populations were very healthy and fishing mortality was low. Recruitment in 2007 was very good, so population increases in size and numbers should continue. The length structures of the populations that we sample also indicate that the abundance of larger white perch should continue to increase in 2009.
Yellow perch runs during the spring of 2008 were pretty good in spite of the temperamental spring weather. An assessment of upper Bay populations indicated that abundance increased over the last few years to levels last seen in the late 1990’s. Fishing mortality was estimated to have decreased since 2004, and currently is at very low levels. Interestingly, there were more reports of summertime anglers having very good success in finding keeper yellow perch. Spring fishing during 2009 should be very good in the upper Bay and in the Choptank River. Anglers are reminded to look for tags on yellow perch. Anglers who send in tag information will receive a DNR yellow perch hat as a reward. In addition, anglers are reminded that there is an on-line yellow perch angler creel survey on the DNR web page, or by clicking this link: www.dnr.state.md.us/fisheries/survey/vasurvey.html.
Simply log in and provide information on where you fished and what yellow perch you caught. The information has proved very useful in our assessments.
Over the last 10 years Maryland’s commercial American eel fishery ranks #1 among all Atlantic coastal states, accounting for more than 40% of the total American eel harvest. Average annual eel landings over this period were approximately 300,000 pounds. American eels are harvested bay wide in both the main stem and nearly all tributaries in Maryland’s tidal portion of the Chesapeake Bay. Over 95% of the eels are captured with eel pots.
Since 1997, DNR Fishery Service has conducted an American eel study. Major components of this study include collection of harvest data from the commercial eel fishery, monitoring of the eel fishery through representative subsampling of commercial catches, the development of American eel size and age structure in selected tributaries of the Chesapeake Bay, an eel pot study in the Sassafras River, and an annual young of year abundance survey in the Coastal Bays.
Results to date indicate that the juvenile eel index marked its high in 2007, but catches in 2008 slipped below the nine year average. The overall nine year juvenile index shows no apparent trend. Yellow eel relative abundance indices based on commercial landings continued to show a positive trend through 2007. Commercial eeling effort continued to decline, but landings have remained stable. The yellow eel relative abundance index from our eel pot sampling has shown slight improvements with 2008 catches ranking 2nd over the past six sampled years.
DNR also participates in multi-state management of the American Eel through multiple technical committees established by the Atlantic States Marine Fisheries Commission (ASMFC). ASMFC, which was formed 65 years ago by the 15 Atlantic coastal states, has management authority for 22 inter-jurisdictional species groups.
Fish Habitat Project
The primary objective of Fish Habitat Project is to evaluate the concept of using impervious surface reference points (ISRPs) as a tool for fish habitat management in much the same way as current fisheries management is using biological reference points (BRPs) to determine how many fish can be safely harvested from a stock.
Dissolved oxygen is an ideal response variable in the development of ISRPs because fish require well-oxygenated water and because it can provide insight into both the metabolic and pollution status of a waterbody. 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).
By most measures, human impacts have grown faster than the population. Land is converted to impervious surface (paved surfaces, buildings, and compacted soils) as human population grows. 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.
It is recognized that development per se, urbanization and industrialization, contribute significantly to contaminant loads, eutrophication, and physical degradation of coastal areas. Therefore habitat issues associated with impervious surface are not limited to just dissolved oxygen. 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.
The Fish Habitat Project, along with citizen volunteers and personnel from Harford County, deployed drift nets during March and April 2008 in the flowing freshwater portion of selected tributaries of the Bush River to document the presence of anadromous fish eggs and larvae. Project personnel and citizen volunteers also sampled Mattawoman and Piscataway creeks, tributaries of the Potomac River for anadromous fish eggs and larvae. Overlapping with this activity in March and continuing into April, project personnel pulled plankton nets in the tidal portions of the South River and Mattawoman and Piscatawy creeks 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 2008 (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 Nanjemoy 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 2008 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 than in the highly developed portion.
Water quality in the areas sampled in 2008 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 2009 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.
Click here to view recent bay satellite images at mddnr.chesapeakebay.net/NASAimagery/EyesInTheSky.cfm