Assessment and management techniques for migratory annual squid stocks: the Illex argentinus fishery in the Southwest Atlantic as an example

Basson, M.; Beddington, J. R.; Crombie, J. A.; Holden, Simon; Purchase, Lynne V.; Tingley, G. A.

doi:10.1016/0165-7836(96)00481-x

Cited by 70 publications

(66 citation statements)

References 9 publications

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“…The number of licences issued per year was used as a measure of effort and catch per unit effort was calculated as tonnes of squid per vessel per year for this period. The fishery is effort limited and operates by issuing a limited number of licenses that allow fishing for a fixed period of time (see Beddington et al 1990, Basson et al 1996. Using licenced vessels as a measure of effort 1s in accordance with the way in which the fishery is managed.…”

Section: Methodsmentioning

confidence: 99%

“…The species does not exhibit a clear stock recruitment relationship and estimates suggest that spawning stock biomass can vary by a factor of 10 between successive years (Csirke 1987). For a given size of spawning stock the adult population can vary enormously (Csirke 1987, Beddington et al 1990, Basson et al 1996. The short lifespan completed within a complex oceanographic environment means that catches exhibit considera.ble inter-ann.ua1 variability.…”

Section: Introductionmentioning

confidence: 99%

“…comm.). The Falkland Islands fishery consists almost exclusively of winter spawners (Csirke 1987, Basson et al 1996 and it is assumed that the fishery targets a single stock (the SPS) south of 45" S (Basson et al 1996). Illex argentinus migrates between spawning grounds in the northern Patagonian shelf and feeding grounds in the south.…”

Section: Introductionmentioning

confidence: 99%

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Influence of oceanographic variability on recruitment in the Illex argentinus (Cephalopoda:Ommastrephidae) fishery in the South Atlantic

Waluda¹,

Trathan²,

Rodhouse³

1999

Mar. Ecol. Prog. Ser.

122

114

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'~e p a r t m e n t of Zoology, University of Aberdeen. Tillydrone Avenue, Aberdeen AB24 2TZ, United Kingdom ABSTRACT: The fishery for IUex argentinus in the Southwest Atlantic is subject to large inter-annual variability in recruitment strength. In this paper we attempt to build a predictive model using sea surface temperature (SST) to examine links between recruitment to the Falkland Islands fishery and environmental variability during the juvenile and adult life history stages. SST data from the National Center for Atmospheric Research (NCAR) were found to be comparable with near-surface data derived from in situ expendable bathy-thermograph (XBT) profiles in the southern Patagonian shelf. Variation in SST during the early Me stages appears to be important in determining recruitment of I. argentinus.SST in the hatching grounds of the northern Patagonian shelf during the period of hatching (particularly June and July) was negatively correlated with catches in the fishery in the following season. SST anomaly data from positions in the Pacific and Southwest Atlantic were used to examine teleconnections between these areas. Links were seen at a lag of 2 yr between the Pacific and southern Patagonian shelf, and at about 5 yr between the Pacific and northern Patagonian shelf. This is consistent with SST anomalies associated with El Nifio in the Pacific propagating around the globe via the Antarctic Circumpolar Wave (ACW). Predicting cold events via teleconnections between SST anomalies in the Pacific and Atlantic would appear to have the potential to predict the recruitment strength of I. argentinus in the Southwest Atlantic.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of oceanographic variability on recruitment in the Illex argentinus (Cephalopoda:Ommastrephidae) fishery in the South Atlantic

Waluda¹,

Trathan²,

Rodhouse³

1999

Mar. Ecol. Prog. Ser.

122

114

View full text Add to dashboard Cite

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“…In this approach, information obtained from fishing vessels is applied in real time to determine at what point the fishery should be closed, thus regulating the catch. Real-time management is presently utilized in some squid fisheries (Agnew et al, 1998;Basson et al, 1996;Rosenberg et al, 1990;Morales-Bojórquez et al, 2001), but has not yet been implemented in any U.S. squid fishery. A key issue is the development of an approach to measure catch per unit effort (CPUE) during the course of the season without distributing an uneconomical number of observers within the fleet.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Real-time Catch and Effort Reporting in the U.S. Ilex illecebrosus Fishery

Powell¹,

Bonner²,

Mann³

et al. 2003

J. Northw. Atl. Fish. Sci.

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The Illex illecebrosus fishery in the northwestern Atlantic Ocean is a trawl-based fishery. Illex illecebrosus normally lives less than one year, thus managing the fishery using a standard stock assessment approach is difficult. Real-time management is an attractive option. The purpose of this study was to investigate the validity and utility of data reported by commercial vessels for application in real-time management in the I. illecebrosus fishery. The assessment includes evaluating the frequency of erroneous reports, identifying the best measures of effort for catch per unit effort (CPUE) analysis, and examining the influence of vessel type and vessel behavior on subsequent analyses of trends in catch and effort.Incomplete reports occurred 24% of the time in the commercial data. Misreported times and positions occurred less than 1% of the time. Searching time was not discriminated consistently. Searching times and distances were recovered from the more accurately-reported data on tow times and tow positions. Tow duration was more accurately estimated from Captains' reports than tow distance. True distances were underestimated by 1020% using the position of net deployment and retrieval to measure tow distance because tows did not follow a straightline path. Effort could be estimated based on tow distance or tow duration. Duration was the most accurate effort term. Searches between tows did not improve subsequent catch. Similarly, overnight transits, arguably a type of searching behavior, did not improve the subsequent day's catch. Thus, vessels, on the average, would have improved trip economics by not searching. Because of the apparent absence of a positive effect of searching and the lower accuracy of searching time and searching distance in comparison to tow-based metrics, particularly tow duration, addition of searching time or searching distance to effort did not materially improve the measurement of CPUE.RSW (refrigerated seawater) trawlers search much less often than freezer trawlers. As a consequence of lower catch and longer duration tows, the CPUE for RSW trawlers is distinctly lower than for freezer trawlers. Catch per tow was higher by more than a factor of two for larger vessels. As a consequence of the higher catch and longer tows, CPUE was significantly higher also for the larger vessels. Managing the I. illecebrosus fishery using an industry-based reporting scheme would require information from freezer and RSW trawlers and specified vessel size categories.

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“…Moreover, the number of licenses must also consider the effort and the efficiency of the fleets. Thus, recruitment estimates will allow to amend problems associated with changes in the efficiency of the fleets, principally variations in the catchability (Basson et al, 1996) or in the fishing power (Rosenberg et al, 1990;Basson and Beddington, 1993). …”

Section: Discussionmentioning

confidence: 99%

Population size and exploitation of giant squid (<i>Dosidicus gigas</i> D'Orbigny, 1835) in the Gulf of California, Mexico

et al. 2001

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Assessment and management techniques for migratory annual squid stocks: the Illex argentinus fishery in the Southwest Atlantic as an example

Cited by 70 publications

References 9 publications

Influence of oceanographic variability on recruitment in the Illex argentinus (Cephalopoda:Ommastrephidae) fishery in the South Atlantic

Influence of oceanographic variability on recruitment in the Illex argentinus (Cephalopoda:Ommastrephidae) fishery in the South Atlantic

Evaluation of Real-time Catch and Effort Reporting in the U.S. Ilex illecebrosus Fishery

Population size and exploitation of giant squid (<i>Dosidicus gigas</i> D'Orbigny, 1835) in the Gulf of California, Mexico

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