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This research will involve intensive field work on the Raritan River near New Brunswick and on the open ocean off the coast of New Jersey, and some lab and data analysis work, including:
1. Wading in the Raritan River and capturing fish with nets
2. Assisting with fish trap deployment and retrieval on small vessels on the open ocean
3. Weighing and measuring fish and crustaceans and removing fish scales for aging
4. Tagging fish with small electronic tags
5. Downloading data from two remote antennas and a video monitor
6. Analyzing fish passage data to determine how long it takes for fish to pass through a fish ladder
7. Viewing video to ID and count fish passing through a fish ladder
Background
New Jersey fisheries, both commercial and recreational, are economically valuable and of cultural importance. However, a complex set of factors affect fish populations, including fishing pressure and changes in habitat. In order to understand the changes that are occurring, we utilize a variety of techniques to assess fish populations and their distribution. Reliable data on the relative abundance fish populations are important for accurate stock assessment models and informing fishery management. The successful applicant will participate in two ongoing research projects to gain a more complete perspective of New Jersey fisheries.
Shad and River Herring
Mid-Atlantic populations of river herring (Alosa pseudoharengus and A. aestivalis) and American shad (A. sapidissima) - collectively referred to here as alosines - have declined precipitously in recent years. River herring are now listed as “Species of Special Concern” by the National Marine Fisheries Service. With over 1,700 dams in New Jersey, barriers to spawning migration are one of the most important impediments to restoration of river herring and shad populations in this state. At many dams, fish passage structures have been installed to facilitate upstream passage of anadromous fish. The New Jersey Department of Environmental Protection (NJDEP) has conducted limited monitoring at some fish passage structures to determine whether anadromous fish are capable of passing upstream and, in a few cases, to count the number of individuals that emerge from the upstream end. While it is encouraging to know that some individuals are able to pass, the more relevant question from a restoration perspective is: to what extent do dams with fish passage structures still impede migration of alosines and what, if anything, can be done to reduce this impediment?
Delays incurred at fish passage structures are known to exact a bioenergetic cost for alosines and may contribute heavily to mortality and reduced iteroparity (return spawning migrations) as alosines rely on limited energy stores to power their freshwater migrations. Such delays may even be greater than the time spent actively migrating, and when fish ladders are not well designed and properly operated, they may prevent passage of a large fraction of the spawning population. There are two components to migratory delay: time spent searching for the fish passage structure (attraction time) and time to pass through the structure (transit time). While body condition of individual fish is beyond our control, flow rates through fish passage structures can often be modified with relatively little effort or cost. The major impediment is our understanding of how attraction and transit time vary with flow for different anadromous species.
Reef Species
Bottom trawls are commonly used to survey marine fishes. However, trawls may fail to adequately assess structure associated species like black sea bass, tautog, and lobster which primarily occupy habitats (such as wrecks and rocky reefs) which cannot safely be trawled. Therefore, there is a need for alternative or supplementary surveys using fixed-gears (e.g., traps, longlines, rod-and-reel) that are more effective at sampling these habitats.
The New Jersey Department of Environmental Protection (NJDEP) Division of Fish and Wildlife has a large artificial reef program to support marine life and improved fishing and diving opportunities. The reefs are constructed by sinking concrete and metal structures at designated artificial reef sites. We are conducting a multi-year ventless trap survey on three of New Jersey’s artificial reefs. Traps are deployed and monitored on the reefs each spring, summer, and fall. The relative abundance and biological data collected from the trap catches will provide insights into changes in community composition between years, seasons, reefs, and substrate types.
Project Goals and Objectives
The broader goal of the proposed research is to assess fish populations using a variety of tools and techniques, including large nets, fish traps, electronic tags, and video recording.
Raritan River Study
This research will improve our understanding of how fish passage structures may reduce impediments to spawning migrations for shad and river herring. This project is particularly timely and relevant in light of recent and planned dam removals on the Raritan River. Dam removal can be an important component of anadromous fish restoration; however, dam removals can only be successful if they allow anadromous fish to migrate freely between the ocean and their freshwater spawning habitat. If other potential obstacles, such as the Island Farm Weir, remain, then removal of other dams will not, by itself, be sufficient to restore anadromous fishes.
Our objectives are:
1. To estimate attraction and transit times, overall migratory delay, and passage rates (fraction of individuals arriving at the ladder which pass through the upstream end) for American shad and river herring at the fish passage structure on the Island Farm Weir (IFW) in Bound Brook, NJ.
2. To understand how endogenous (length, weight, age, sex, species) and exogenous factors (water velocity and temperature) influence attraction and transit times and overall migratory delay.
Trap Survey
This study will provide information about the community composition and relative abundance of reef inhabitants. This information will be of immediate utility for New Jersey fishery managers through a characterization of seasonal changes in the fish and invertebrate communities inhabiting the reefs, and for artificial reef design through a comparison of fish and invertebrate abundance between different artificial reef materials. This project will also provide information about the efficacy of traps as a reef survey technique. Our objectives are:
1. To characterize seasonal and spatial variation in community composition and relative abundance of structure-associated species on artificial reefs off of New Jersey.
2. To develop survey design recommendations for a long-term trap survey for New Jersey.
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