Fisheries Ecosystem Assessment Division Sampling Studies

Larval Yellow Perch Presence and Absence Study

Yellow perch larval sampling is conducted in tidal rivers in the spring beginning in later March and continuing through April. Ichthyoplankton nets are towed behind a boat for 2 minutes and the nets are examined to determine if yellow perch larvae are present. Sampling is done twice a week and generally 50 samples are collected. The data collected during this study will be compared to historical data to determine the survival rates of larval yellow perch in the rivers sampled.

ichthyoplankton net Yellow Perch larvae

Yellow Perch in RNALaterLarval Yellow Perch RNA:DNA Study

This is the first year for this study; we will be collecting yellow perch larvae for analysis for the ratio of ribonucleic acid (RNA) concentration to deoxyribonucleic acid (DNA) concentration in body tissue. This ratio is a useful indicator of nutritional status and growth in larval fish. The data from this study can provide connections to feeding success and larval condition.

Larval Yellow Perch Feeding Analysis Study

Yellow Perch gutYellow perch post-larvae will be collected for this study and the gut will be analyzed for fullness and food content. This study investigates whether feeding success and diet composition (1) influenced yellow perch presence and (2) reflected the level of development indicated by counts of structures per hectare (C / ha) from tax maps. In the 2010 Fisheries Ecosystem Assessment Division annual report, analyses indicated that watershed development negatively influenced survival of yellow perch larvae. First-feeding success may be an important factor influencing larval yellow perch survival that is negatively influenced by development.

Stream Ichthyoplankton Study

Fisheries Ecosystem Assessment Division​​ is working to understand how habitat changes impact Maryland's fisheries in the Chesapeake Bay. This study primarily focuses on understanding how urbanization limits habitat for fish, which could affect spawning success. In order to access the affects of habitat change, ichthyoplankton (fish eggs and larvae) are sampled using a ichthyoplankton net attached to a square frame on a pole in the water for 5 minutes in several tributaries to help identify the presence and absence of anadromous fish (herring, shad, white perch, and yellow perch) spawning and spawning habitat quality.

Ichthyoplankton sampling Picking through ichthyoplankton samples

Estuarine Fish Community Sampling Study

Fisheries Ecosystem Assessment Division​​ is evaluating nursery and adult habitat of recreationally important finfish in subestuaries of the Chesapeake Bay to see how development, indicated by the density of structures (houses, businesses, etc.) impact the habitat of finfish. We sample sites in Bay subestuaries (tributaries of the main Bay) using otter trawls and beach seines. Beach seines sample shallow water habitat and the trawls are towed in the deeper channel adjacent to shore. Sites are sampled once every two weeks during July through September. Target species are striped bass, yellow perch, white perch, alewife, blueback herring, American shad, spot, Atlantic croaker, and Atlantic menhaden. Juveniles and adults are separated and counted, and adults are measured. In addition to beach seining and trawling, water quality measurements is taken at each site.

Sampling Beach seining

Conductivity Study

Fisheries Ecosystem Assessment Division​​​​​​​​ began this study in 2014 to continuously monitor conductivity levels at four different tributaries of subestuaries of the Chesapeake Bay. The data loggers will continuously record conductivity measurements over a year providing insight into deteriorating spawning habitat.  Elevated conductivity is a very good indicator of urbanization impacting a stream. Additional data loggers will be deployed in other tributaries in 2015.

Map of Piscataway Creek conductivity measurements.

Piscataway Creek conductivity measurements Volunteer with data logger 

For additional information see Reports and Publications page or contact Jim Uphoff.