Project Summary - Drop Chain

AN EVALUATION OF THE AVOIDANCE GEAR 12" DROP CHAIN SWEEP AS A METHOD TO REDUCE WINTER FLOUNDER RETENTION IN THE SMALL MESH SQUID TRAWL FISHERY WITHIN THE SNE/MA WINTER FLOUNDER STOCK AREA

 



Project Summary

 

 

This project will evaluate winter flounder discard reduction in the directed small mesh Loligo squid fishery by using a gear adaptation that consists of a 12" drop chain sweep coupled with a 24" headrope adjustment.   This project will utilize and expand upon the information on drop chain performance generated by the proof of concept project conducted by CCE in 2010.  Collaboration with the commercial fishing industry to develop and to study this avoidance gear adaptation will hopefully improve fishing practices. The goal is to allow fishermen to fish more selectively.  Selective harvesting approaches will also contribute to the rebuilding of fish stocks and in particular, with this project, the population of winter flounder.

 

The Loligo squid fishery is of vital importance to the economic health of many commercial fishing communities, particularly in the Mid-Atlantic (MA) and Southern New England (SNE) areas.  Winter flounder stocks of the MA and SNE regions have been identified as severely depleted. Winter flounder are often a bycatch specie in the economically significant small mesh squid trawl fishery of the MA/SNE areas. The specific complexity of this problem is rooted in the co-occurrence of winter flounder and Loligo squid.  The problem is further exacerbated by the need to rebuild the winter flounder stocks while minimizing the economic impacts on the Loligo fishery.

 

Fishermen must use small-mesh bottom trawls to capture Loligo squid, which cannot be retained by standard groundfish mesh sizes. This fishery is subject to bycatch limits when such trawls are used in areas where regulated species, such as winter flounder reside. Bycatch of winter flounder in the small-mesh bottom trawl fishery for Loligo squid in the northwestern Atlantic is a concern of fishery management.  Therefore, avoidance of winter flounder during fishing activities is imperative at this time in order to reduce fishing mortality and assist rebuilding efforts.

 

For this project, the primary goal is to determine the functional performance of the 12" drop chain sweep with a 24" headrope adjustment as an effective method to reduce winter flounder bycatch while maintaining Loligo squid capture.  There are two principle effects that a longer drop chain creates that are beneficial to reducing bycatch.  The first is that a longer drop chain increases the distance between the footrope and the sweep providing more area for escapement.  Secondly, is that increasing the length of the drop chain makes it possible for the sweep to travel behind the footrope.   This is important because with the sweep behind the footrope, the mud cloud created by the sweep does not obscure the gap between the footrope and the sweep.  By keeping this gap visible, it should increase opportunities for flounders and other species to avoid capture.  This gear will be tested across a wide range of fishing strata including time, area, fishing practice, and fishing vessel size and power in the small mesh squid fishery.  Additional testing of this avoidance gear adaptation would improve the statistical strength of the previous study and develop a more robust assessment of the effectiveness of this type of gear.  This in turn provides the industry an opportunity to evaluate fishing methods that avoid winter flounder and could be adopted on a voluntary or required basis.  It is also important to seek avoidance gear adaptations that do not drastically impact fishermen economically.  A successful design would therefore be easily retrofitted to pre-existing gear and would not reduce the harvest of target species to levels below economic viability

 

Scientific Design

We propose to use 2 pairs of fishing vessels representative of the small mesh squid trawl fleet to compare an experimental net with a 12" drop chain sweep with a 24" headrope adjustment to a control net (standard 5" drop chain sweep) with zero slack in the headrope. Both vessel pairs are comprised of similar sized vessels with identical nets. The unaltered trawl nets (control nets) are typical of the small mesh net used in the squid fishery along the east coast of the US. Both vessel pairs have characteristics reflective of the two different size classes of vessels that are active in this fishery.

 

A paired-tow scientific design will be utilized.  Two similar vessels will fish side-by-side: one vessel towing the control net; one vessel towing the experimental net with the 12" drop chain sweep. Control nets and experimental nets will be the same except for the sweep. The control net will have a standard 5" sweep.  The experimental net will have the 12" drop chain sweep installed.  On the experimental net, the headrope will be slacked at 24". The control net will have zero slack in the headrope in order to have the least escapement possible.

 

Statistical analysis will determine if the avoidance gear 12" drop chain sweep with a 24" headrope adjustment significantly reduces retention of winter flounder relative to the standard control net. Videotape recordings will be made during as many tows as possible and where conditions permit.  A self-contained video camera and recording system will be attached to the headrope of the net.  It will be positioned to look down and back towards the footrope and sweep of the net.  Videotape will be analyzed on a frame-by-frame basis and ethograms (behavioral pathways) will be constructed for each of the target species.  This analysis, should it successfully identify species-specific behavior patterns, will be used as the basis for making recommendations regarding potential changes to the mouth of the net to reduce bycatch of non-target species

 

This project will provide direct, practical results to assist the fishing industry and fishery managers to address the flatfish bycatch issue in the small mesh trawl fishery.  This study will statistically verify the ability and efficiency of the gear design in reducing winter flounder bycatch.  We will also provide video documentation of species behavior to the net.  This information can be used to refine the 12" drop chain sweep and offer information on other possible gear technologies.  The project will use the gear commonly used in the small mesh Loligo fishery and will thus have direct applicability for fishermen. This project will provide timely, accurate and credible data to be used for science based management strategies that protect and rebuild fisheries resources while minimizing impacts to fishing communities. The objective of collaborative efforts with industry is to achieve both the sustainability of the fishery resources important to Southern New England and the sustainability of the livelihoods and economic well-being of the harvesters and coastal communities that depend on these resources.