The DNREC Division of Fish and Wildlife monitors the status of a wide variety of marine finfish and shellfish populations in the Delaware Estuary and Inland Bays through its bottom trawl survey program.

The Division’s trawl surveys are among the longest-running state surveys on the East Coast.

A 30-foot trawl survey was initiated in 1966 and is primarily used to monitor sub-adult and adult fish abundance.

The 16-foot trawl has been conducted since 1980 and is used to monitor juvenile fish and crab abundance.

For more information, or to request data, please contact Trawl & Oyster Projects Leader Audrey Ostroski, at ostroski.audrey@delaware.gov or 302-735-2967.

How it Works

To take a survey, a trawl net is towed for a specified time at a number of fixed sites. After the tow, the net is hauled up and emptied on the deck.

The sample is sorted by species and the fish are measured and weighed. Scale and/or otolith (ear bone) samples are removed from a portion of the Weakfish, Northern Kingfish, Striped Bass, Summer Flounder and Atlantic Menhaden catches to determine the age of the fish.

Over 160 species of marine finfish and invertebrates have been recorded in survey catches since their inception. Survey catches are typically dominated by species such as Bay Anchovy, Hogchokers, Weakfish, Atlantic Croaker and Spot.

Survey Data

Data from both surveys are used to generate statistical measures of relative abundance that fisheries managers can use to monitor population trends. Used in conjunction with data from other state and federal surveys, this information helps managers develop coast-wide stock assessments and fishery management plans.

The surveys also serve as important platforms for collecting specimens for research into subjects such as genetics, contamination by pollutants, age and growth of fish and fish movements, through tagging.

The surveys are an indispensable part of Delaware’s marine fisheries program.

Related Topics:  fish anc wildlife, fisheries, research, trawl