Article

Evaluating the Effects of Two Coastal Mobile Gear Fishing Closures on Finfish Abundance off Cape Cod

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Abstract

A 16-year time series of research trawl catches, commercial landings, and effort data were used to evaluate two areas protected from mobile gear fishing off Cape Cod, Massachusetts, and assess effects of the spring otter trawl fishery for longfin squid Loligo pealeii on local abundance of finfish frequently caught as bycatch. Catch rates were compared between a seasonal closure, a permanent closure, and adjacent waters open to mobile gear fishing. Winter flounder Pleuronecles americanus and scup Stenotomus chrysops were more abundant in the two protected areas. Black sea bass Centropristis striata and windowpane Scophthalmus aquosus were more abundant in the seasonal closure but not in the permanent closure. Abundance indices of summer flounder Paralichthys dentatus and longfin squid were not significantly different between the seasonal closure and the exploited area but both species were less abundant in the permanent closure. Little skate Raja erinacea were more abundant in areas open to trawling. Significantly lower catch rates of the latter four species in the permanent closure indicated that habitat differences were important in determining local abundance. Decreased local density of finfish in open areas was not related to inshore spring squid trawling effort or landings. Regional trawl effort on Georges Bank and in southern New England did have significantly negative effects on local finfish density. Inferences of causal relationships between the inshore squid fishery and decreased local abundance of finfish were not supported. These results suggest that inshore abundance of these species is more related to total regional trawl effort.

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... In the waters off the northeastern United States, many stocks of commercial and recreational species have declined in recent years (Anthony, 1993;Sissenwine and Rosenberg, 1994;Collins, 1995;Matthiessen, 1995;NEFSC, 1995). Although much of the blame for these declines is ascribed to sustained overfishing, there also has been substantial concern over bycatch and discarding practices in key fisheries of the region, especially those involving demersal trawling Howell andLangan, 1987, 1992;Cadrin et al., 1995;Kennelly et al., 1997). ...
... As predicted by Wilk and Brown (1980) some time ago, one of the causes of mortality for young scup in this region is thought to be the incidental bycatch and subsequent discarding of this species from demersal trawlers that target other species, particularly squid (Loligo spp.). McKiernan and Pierce's 2 study of the inshore squid fishery in Nantucket and Vineyard Sounds, Massachusetts, showed significant discard of scup but, like Cadrin et al. (1995), they concluded that the inshore abundances of this species were more probably related to trawl effort throughout the region than to the relatively small effort of inshore squid trawlers. They concluded that significant numbers of small scup may be discarded by squid trawlers farther offshore where scup are known to migrate in the autumn (see also Finkelstein, 1971;Eklund and Targett, 1990) and recommended an examination of the discarding practices of these trawlers. ...
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In the waters off the northeastern United States, many stocks of com-mercial and recreational species have declined in recent years (An-thony, 1993; Sissenwine and Rosen-berg, 1994; Collins, 1995; Ma-tthiessen, 1995; NEFSC, 1995). Al-though much of the blame for these declines is ascribed to sustained overfishing, there also has been substantial concern over bycatch and discarding practices in key fisheries of the region, especially those involving demersal trawling (Murawski, 1994; Howell and Langan, 1987, 1992; Cadrin et al., 1995; Kennelly et al., 1997). For many years scup (or porgy, Stenotomus chrysops) has been an important commercial species in the mid-Atlantic and southern New England regions, caught princi-pally by otter trawling and to a lesser extent by pound nets, float-ing trap nets, and fish traps (Shep-herd and Terceiro, 1994). Like many other key species in the re-gion, annual commercial landings of this species have declined mark-edly in recent years from between 18,000 and 27,000 metric tons (t) in the 1950s and 60s to 6000 t in 1992 and 4400 t in 1993 (NEFSC, 1995). There is also an important recreational fishery for scup in this region, and recreational landings in recent years have accounted for 20. to 50% of the total annual catch. These have also declined from an estimated 3,100 t in the 1980s to 2100 t in 1992 and 1300 t in 1993 (NEFSC, 1995). Scientists at the 1995 Northeast Regional Stock As-sessment Workshop for the scup stock in this region concluded that 1) it is currently overexploited; 2) it is at a low level of biomass; and 3) current high rates of exploitation of age 0–2 fish should be decreased as much as possible (NEFSC 1). As predicted by Wilk and Brown (1980) some time ago, one of the causes of mortality for young scup in this region is thought to be the incidental bycatch and subsequent discarding of this species from de-mersal trawlers that target other species, particularly squid (Loligo spp.). McKiernan and Pierce's 2 study of the inshore squid fishery in Nantucket and Vineyard Sounds, Massachusetts, showed significant discard of scup but, like Cadrin et al. (1995), they concluded that the inshore abundances of this species were more probably related to trawl effort throughout the region than to the relatively small effort of inshore squid trawlers. They concluded that significant numbers of small scup may be discarded by squid trawlers farther offshore where scup are known to migrate in the autumn (see also Finkelstein, 1971; Eklund and Targett, 1990) and recom-mended an examination of the dis-carding practices of these trawlers. The most reliable way to quan-tify discards in commercial fisher-ies is for observers to record data during normal fishing operations (e.g. Jean, 1963; Powles, 1969; Young and Romero, 1979; Atkinson, 1984; Murawski et al., 1995). Infor-mation from such programs is a necessary prerequisite for the two main management alternatives used to reduce discards: 1) spatial and temporal closures to fishing in areas and times of high rates of dis-card of key species (i.e. discard "hot-spots") (Murawski, 1992; Hendrick-son and Griffin, 1993; Alverson et al., 1994, Kennelly, 1997); and 2) modifications to fishing gears and practices that improve selectivity (Robertson and Stewart, 1988; Isaksen et al. Fisheries Service's Northeast Fish-eries Science Center (NEFSC) has operated a large-scale observer pro-gram in many of the fisheries off the northeastern United States from Maine to North Carolina (Murawski et al., 1995; Kennelly et al., 1997). The data collected from demersal trawlers in this program have provided an opportunity to examine the spatial and temporal occurrences of discarded scup in the offshore mid-Atlantic and southern New England trawl fishery.
... Many national and international policies are geared towards creating marine protected areas (Chape et al. 2005), and many countries are now prioritizing marine spatial planning (Douvere 2008;Stelzenm et al. 2012). Common fisheries management strategies include gear restrictions in certain areas or seasonal closures (Cadrin et al. 1995;Panjarat and Bennett 2012). In order to evaluate the effectiveness of conservation and management strategies, spatial data are required on species (Moller and Berkes 2004), habitats (Chape et al. 2005), and human activities (Reid 2007). ...
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Do fishers know best when it comes to identifying areas with rare and depleted fish species? The global conservation crisis demands that managers marshal all available datasets to inform conservation management plans for depleted species, yet the level of trust placed in local knowledge remains uncertain. This study compares four methods for inferring species distributions of an internationally traded, rare and depleted genus of marine fishes (Hippocampus spp.): the use of (i) fisher interviews; (ii) government research trawls, (iii) scientific diving surveys, and (iv) citizen science contributions. We analyzed these four datasets at the genus and individual species levels to evaluate our conclusions about seahorse spatial occurrence, diversity of species present and the cost effectiveness of sampling effort. We found that fisher knowledge provided more information on our data-poor fish genus at larger spatial scales, with less effort, and for a cheaper price than all other datasets. One drawback was that fishers were unable to provide data down to the species level. People embarking on conservation endeavors for data-poor species may wish to begin with fisher interviews and use these to inform the application of government research, scientific diving, or citizen science programs.
... Efforts to model the effects of closures have become more prevalent in recent literature (Adlerstein and Trumble, 1998;Hobday and Hartmann, 2006;Grantham et al., 2008;Powers and Abeare, 2009;Diamond et al., 2010) and can be informative for management decisions on size, location, and duration of closures to meet bycatch reduction objectives. Additionally, there is a large body of literature on the effectiveness of closed areas and marine protected areas as a tool for fisheries management (Cadrin et al., 1995;Gubbay, 1995;Murawski et al., 2000;Edgar et al., 2007). ...
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Designing effective bycatch mitigation programmes requires an understanding of the life histories of target and non-target species, interactions of fish and fishing gear, effects of spatial and temporal shifts in fishing effort, socio-economic impacts to the fishery, and incentives of fishery participants. The effects of mitigation measures (including fishing gear modification, time/area closures, bycatch quotas and caps, incentive programs, and fleet communication programs) have been evaluated with respect to reducing bycatch and discards. Less attention has been focused on evaluating unanticipated results related to shifts in fishing effort, changes in the size of non-target species caught, reduced catch of target species, and economic viability to fishing fleets. Time/area closures, bycatch quotas/caps, and fleet communication programmes were evaluated against a set of criteria to assess overall effectiveness in reducing bycatch without causing unintended biological and socio-economic impacts. The results suggest that wide-ranging studies of species' life histories, potential changes in fleet behaviour, and individual incentives are important for developing and implementing mitigation programmes. Combining a suite of mitigation techniques has been successful in meeting biological and socio-economic fisheries goals. Additionally, collaborative programmes that utilize the skill sets of fishers, scientists, and managers have increased effectiveness in meeting bycatch reduction objectives.
... The distribution of fish, however, may not obey the sampling design, particularly if environmental gradients shift the structure of the fish population (e.g. Brandt and Wadley, 1981;Cadrin et al., 1995) along a spatial gradient different from the gradient in sample density. Errors of some magnitude can be expected if areas of low sampling density yield the largest catches (see also Smith and Gavaris, 1993;van der Meer, 1997). ...
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The trend towards use of commercial vessels to enhance survey data requires assessment of the advantages and limitations of various options for their use. One application is to augment information on size-frequency distributions obtained in multispecies trawl surveys where stratum boundaries and sampling density are not optimal for all species. Analysis focused on ten recreationally and commercially important species: bluefish, butterfish, Loligo squid, weakfish, summer flounder, winter flounder, silver hake (whiting), black sea bass, striped bass, and scup (porgy). The commercial vessel took 59 tows in the sampled domain south of Long Island, New York and the survey vessel 18. Black sea bass, Loligo squid, and summer flounder demonstrated an onshore-offshore gradient such that smaller fish were caught disproportionately inshore and larger fish offshore. Butterfish, silver hake, and weakfish were characterized by a southwest-northeast gradient such that larger fish were caught disproportionately northeast of the southwestern-most sector. All sizes of scup, striped bass, and bluefish were caught predominately inshore. Winter flounder were caught predominately offshore. The commercial vessel was characterized by an increased frequency of large catches for most species. Consequently, patchiness was assayed to be higher by the commercial vessel in nearly all cases. The size-frequency distribution obtained by the survey vessel for six of the ten species, bluefish, butterfish, Loligo squid, summer flounder, weakfish, and silver hake, could not be obtained by chance from the size-frequency distribution obtained by the commercial vessel. The difference in sample density did not significantly influence the size-frequency distribution. Of the six species characterized by significant differences in size-frequency distribution between boats, all but one was patchy at the population level and all had one or more size classes so characterized. Although the variance-to-mean ratio was typically higher for the commercial vessel, five of the six cases that were otherwise were among the species for which the size-frequency distribution differed between the two vessels. Thus, the origin of the significant differences observed between vessels would appear to lie in the spatial pattern of the species as it interacts with the tendency for one vessel to obtain large catches more frequently for some size classes. One consequence of differential distribution and catchability is that more large fish were present in the commercial vessel catches than in the survey vessel catches in cases where the two vessels obtained different size-frequency distributions. Application of commercial vessels to the evaluation of size frequency hinges on understanding how to interpret differences among boats, gear, and sampling design. Here we show that key ingredients to this understanding are the degree of nonlinearity in catchability across a range of size classes, the interaction of varying spatial arrangements among size classes and the sampling design, and the interaction of varying spatial arrangements with differential catchability.
... Where MPAs have been employed in the form of permanent or temporary fisheries closures, although benefits of closed areas are not a guaranteed success (Pastoors et al., 2000), such closures can improve spawning stock biomass for some species (e.g. Cadrin et al. 1995; Goñi et al. 2001) particularly where closures occur at nursery grounds (Horwood et al. 1998). Closures, even where temporary, can result in increased abundance , size and improved sex-ratios (Goñi et al., 2001). ...
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Much has been written in recent years regarding the advantages of marine protected areas (MPAs) as conservation tools. The benefits to fisheries have commonly been cited as primary motives in favour of the establishment of MPAs. To date, a good deal has been theorised with regard to the benefit of MPAs to fisheries in their adjacent areas, but there has been little empirical evidence to support or refute hypothetical claims. Considerations for fisheries' benefits are different to those of ecological benefits in several respects. Economically, fishers' livelihoods often depend on the marine reserve being successful. It is not enough to establish that populations of fish are growing due to protection; stocks, as well as individual fish have to be sufficiently large to be catchable by the industry. Furthermore, restrictions in fishable area ought to be compensated for by increases in catches over time. In terms of the biology of the fish themselves, evidence has shown that heavily exploited commercial fish stocks can take much longer to recover from over-exploitation than previously expected. Although there have been several studies that consider the effects of export and spill-over, there have been few that focus on the patterns that these phenomena might have on the surrounding fisheries; many assume that ecological patterns will manifest in the fishery with time. Recently, assessment methods and predictive models have been suggested for fisheries (e.g. Rapfish, Ecopath/Ecosim), some of which have been adapted specifically for MPAs. In this paper we review recent progress in the field of MPA research with particular focus on fisheries assessment. We also identify priorities, and knowledge gaps, for determining and accurately predicting the benefits of MPAs to fishers. & 2008 Published by Elsevier GmbH.
... Some closed areas used as part of fishery management regimes (for single species) produced positive results for crabs (Yamasaki and Kuwahara, 1989), shrimps (Roberts, 1986), spiny lobster (Davis and Dodrill, 1989) and plaice (ICES, 1994). In other ca ses, poor results have been shown when the protected area is located in unfavourable habitats (Heslinga et al., 1984; Tegner, 1993), or is not protecting a sufficient portion of critical habitats (Armstrong et al., 1993; Shepherd and Brown, 1993; Cadrin et al., 1995). In such situations, the establishment of marine reserves could lead to a 10 C M I false sen se of security while antagonising fishers and other stakeholders (Carr and Reed, 1993; Dugan and Davis, 1993). ...
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This paper provides a synthesis of the current literature on the potential of marine protected areas (MPAs) as a management tool to limit the ecosystem effects of fishing, including biological and socio-economic perspectives. There is sufficient evidence to show that fishing can indeed negatively impact ecosystems. Modelling and case studies show that the establishment of marine protected areas, especially for overexploited populations, can mitigate ecosystem effects. Although quantitative ecosystem modelling techniques incorporating MPAs are in their infancy, their role in exploring scenarios is considered crucial. Success in implementing MPAs will depend on how well the biological concern, and the socioeconomic needs of the fishing community are reconciled. Ussif Rashid Sumaila, Chr. Michelsen Institute, Bergen, Norway /Fisheries Centre, University of British Columbia, Vancouver, Canada Sylvie Guenette, Fisheries Centre, University of British Columbia, Vancouver, Canada Jackie Alder, School of Natural Sciences, Edith Cowan University, Joondalup, Australia David Pollard, NSW Fisheries Research Institute, Cronulla, Australia/Station Marine d "Endourne, Marseille, France Ratana Chuenpagdee, Institute for Resources and Environment, Vancouver, Canada
... Several studies suggest that these substitution effects may be quite significant. For example, Cadrin et al. (1995) point out that when stocks are migratory, closure of inshore areas to more efficient vessels " may not confer the expected benefits because fishing effort will be displaced to unprotected areas. " Closure of inshore fishing areas led to increased allocation of effort to onshore fishing grounds in the Gulf of Mexico brown shrimp fishery (Gracia, 1997). ...
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The implementation of the Gulf of Mexico Shrimp Fishery Management Plan established an area commonly known as the Tortugas shrimp sanctuary and prohibited all trawling activity within that area between May 15, 1981, and April 15, 1983. Monthly commercial landing statistics of pink shrimp (Penaeus duorarum) were compared between the 2 years of the Tortugas sanctuary closure (i.e., 1981 and 1982), and these data also were compared with similar data from the historical fishery (1960-1979). Landings during the 23 years from 1960 through 1982 averaged 9.7 ± 1.8 million lb/year (mean ± SD); average effort was 16,000 fishing-days/year. Catch per unit effort (CPUE) averaged 619 ± 76 lb/d for the 23 years, and ranged from 797 lb/d in 1980 down to 479 lb/d in 1982. No differences in catch, CPUE, or size composition were distinguishable due to the closure. However, compliance with the regulation by fishermen was poor.
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