scholarly journals Identifying juvenile and sub-adult movements to inform recovery strategies for a high value fishery—European bass (Dicentrarchus labrax)

2021 ◽  
Author(s):  
Thomas Stamp ◽  
David Clarke ◽  
Shaun Plenty ◽  
Tim Robbins ◽  
James E Stewart ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Spatial Ecology ◽  
Juvenile Fish ◽  
Dicentrarchus Labrax ◽  
Fork Length ◽  
Stock Biomass ◽  
Spawning Stock ◽  
High Site ◽  
Poor Recruitment ◽  
The Uk

Abstract The European bass (Dicentrarchus labrax) support high value commercial and recreational fisheries, however the Spawning Stock Biomass (SSB) of the northern Atlantic stock (ICES divisions 4.b–c, 7.a, and 7.d–h) has rapidly declined to an unsustainable level. The decline in SSB has been attributed to high fishing pressure combined with poor recruitment. By tracking juvenile fish their spatial ecology can be identified, and appropriate fisheries management policies designed to boost recruitment can be implemented. Using acoustic telemetry 146 sub-adult European bass (25.2–60 cm fork length) were tracked for up to 370 d across three sites in the southwest of the UK. Tagged fish were detected 2 724 548 times (Range: 166–106 393 detections per fish). Linear modelling estimated tagged fish were resident within 2.4–20.1 km of the site where they were first caught for 42.9–75.5% of the year. Some fish were however resident throughout summer and winter. Individual fish were also tracked moving up to 317 km to other coastal sites, 81% of which returned to their original capture site. Fisheries management should account for the high site fidelity displayed by juveniles and sub-adults of this species and coastal nursery sites should be considered essential habitat.

CCAMLR’s precautionary approach to management focusing on Ross Sea toothfish fishery

2015 ◽  
Vol 27 (4) ◽  
pp. 333-340 ◽  
Author(s):  
Stuart Hanchet ◽  
Keith Sainsbury ◽  
Doug Butterworth ◽  
Chris Darby ◽  
Viacheslav Bizikov ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Management System ◽  
Ross Sea ◽  
Stock Assessment ◽  
Precautionary Approach ◽  
Adaptive Feedback ◽  
Stock Biomass ◽  
Stock Assessments ◽  
Antarctic Marine ◽  
Spawning Stock

AbstractSeveral recent papers have criticized the scientific robustness of the fisheries management system used by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), including that for Ross Sea toothfish. Here we present a response from the wider CCAMLR community to address concerns and to correct some apparent misconceptions about how CCAMLR acts to promote conservation whilst allowing safe exploitation in all of its fisheries. A key aspect of CCAMLR’s approach is its adaptive feedback nature; regular monitoring and analysis allows for adjustments to be made, as necessary, to provide a robust management system despite the statistical uncertainties inherent in any single assessment. Within the Ross Sea, application of CCAMLR’s precautionary approach has allowed the toothfish fishery to develop in a steady fashion with an associated accumulation of data and greater scientific understanding. Regular stock assessments of the fishery have been carried out since 2005, and the 2013 stock assessment estimated current spawning stock biomass to be at 75% of the pre-exploitation level. There will always be additional uncertainties which need to be addressed, but where information is lacking the CCAMLR approach to management ensures exploitation rates are at a level commensurate with a precautionary approach.

scholarly journals Is a management framework based on spawning-stock biomass indicators sustainable? A viability approach

2007 ◽  
Vol 64 (4) ◽  
pp. 761-767 ◽  
Author(s):  
Michel De Lara ◽  
Luc Doyen ◽  
Thérèse Guilbaud ◽  
Marie-Joëlle Rochet
Keyword(s):  
Fisheries Management ◽  
Significant Contribution ◽  
Bay Of Biscay ◽  
Fishing Mortality ◽  
Precautionary Approach ◽  
Management Framework ◽  
Control Approach ◽  
Management Indicators ◽  
Stock Biomass ◽  
Spawning Stock

Abstract De Lara, M., Doyen, L., Guilbaud, Th., and Rochet, M-J. 2007. Is a management framework based on spawning-stock biomass indicators sustainable? A viability approach. – ICES Journal of Marine Science, 64: 761–767: 000–000. Fisheries management agencies have to drive resources on sustainable paths, i.e. within defined boundaries for an indefinite time. The viable-control approach is proposed as a relevant method to deal with sustainability. We analyse the ICES precautionary approach (PA) by means of the notion of viability domain, and provide a mathematical test for sustainability. It is found that the PA based on spawning-stock biomass (SSB) and fishing mortality (F) indicators is sustainable only when recruits make a significant contribution to SSB. In this case, advice based upon SSB, with an appropriate reference point, is sufficient to ensure sustainability. In all other cases, SSB is not a sufficient metric of stock productivity and must be complemented with other management indicators to ensure sustainability. The approach is illustrated with numerical applications to the northern hake and Bay of Biscay anchovy.

scholarly journals An alternative reference point in the context of ecosystem-based fisheries management: maximum sustainable dead biomass

2015 ◽  
Vol 72 (8) ◽  
pp. 2257-2268 ◽  
Author(s):  
Hans-Joachim Rätz ◽  
John Casey ◽  
Steven J. Holmes ◽  
Josep Lloret ◽  
Hendrik Dörner ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Reference Points ◽  
Production Model ◽  
Fish Stock ◽  
Compensatory Mechanism ◽  
Fishing Mortality ◽  
Dead Biomass ◽  
Selection Pattern ◽  
Stock Biomass ◽  
Spawning Stock

Abstract Under the 2013 Reform of the European Union's Common Fisheries Policy (CFP), fisheries management aims to ensure that, within a reasonable time frame, the exploitation of marine biological resources restores and maintains populations of harvested stocks above levels that can produce the maximum sustainable yield (MSY). The CFP also calls for the implementation of an ecosystem-based approach to fisheries management (EBFM). In this paper, we present the concept of maximum sustainable dead biomass (MSDB) and its associated management reference points for fishing mortality and spawning-stock biomass as alternatives to those associated with MSY. The concept of MSDB is illustrated by a dynamic pool production model of a virtual fish stock which takes into account variations in natural mortality (M), fishing mortality (F), and exploitation pattern. Our approach implies a compensatory mechanism whereby survivors may benefit from compensatory density dependence and is implemented through progressive substitution of M with F for varying rates of total mortality (Z). We demonstrate that the reference points for fishing mortality and spawning-stock biomass associated with MSDB are less sensitive to increasing compensation of M with F than those associated with MSY and more sensitive to changes in selection pattern. MSDB-based reference points, which are consistent with maximum stock productivity, are also associated with lower fishing mortality rates and higher stock biomasses than their MSY-based counterparts. Given that selection pattern can be influenced through fishery input measures (e.g. technical gear measures, decisions on areas, and/or times of fishing), whereas variations of M in response to F are not controllable (indeed poorly understood), that the results of many fish stock assessments are imprecise, that maximum stock productivity corresponds to MSDB and that MSY-based reference points may best be considered as limits, we propose that MSDB-based reference points provide a more appropriate basis for management under an EBFM.

scholarly journals The status of sea bass (Dicentrarchus labrax) stocks around England and Wales, derived using a separable catch-at-age model, and implications for fisheries management

2006 ◽  
Vol 64 (2) ◽  
pp. 346-356 ◽  
Author(s):  
Mike G. Pawson ◽  
Sven Kupschus ◽  
Graham D. Pickett
Keyword(s):  
Fisheries Management ◽  
Juvenile Fish ◽  
Model Development ◽  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Commercial Fishery ◽  
England And Wales ◽  
The Status ◽  
Age Model ◽  
Development And Management

Abstract Pawson, M. G., Kupschus, S., and Pickett, G. D. 2007. The status of sea bass (Dicentrarchus labrax) stocks around England and Wales, derived using a separable catch-at-age model, and implications for fisheries management. – ICES Journal of Marine Science, 64: 346–356. The commercial fishery for sea bass (Dicentrarchus labrax) around the coasts of England and Wales developed rapidly in the late 1970s and 1980s and, by 1986, involved some 3000 fishers using more than 2000 boats to make landings worth £3–4 million. The estimated annual catch of sea bass by sport-anglers was similar to the level recorded from the commercial fishery. Sampling of landings showed strong evidence of growth-overfishing in many areas, and a package of technical measures was introduced in 1990 aimed at improving the exploitation pattern and yield per recruit. This paper describes how data collected through a fishery and biological sampling programme around England and Wales over the period 1985–2004 have been utilized in a separable catch numbers-at-age model to assess the dynamics of sea bass stocks in English and Welsh coastal waters. The model output shows that recruitment improved during the 1990s and that moderate levels of fishing mortality allied to an exploitation pattern that largely avoids juvenile fish have enabled the bass population and its fishery to develop sustainably. Results are discussed in relation to model development and management of the bass fishery.

Fishing-induced evolution and changing reproductive ecology of fish: the evolution of steepness

2010 ◽  
Vol 67 (10) ◽  
pp. 1708-1719 ◽  
Author(s):  
Katja Enberg ◽  
Christian Jørgensen ◽  
Marc Mangel
Keyword(s):  
Life History ◽  
Fisheries Management ◽  
Life Histories ◽  
Life History Traits ◽  
Management Practice ◽  
Total Biomass ◽  
Evolutionary Changes ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Stock Recruitment

Fishing can induce evolutionary changes in individual life history traits, leading to fish that mature smaller and younger and with larger gonads, so that they reproduce more intensely. The steepness of a stock–recruitment relationship is commonly defined as the fraction of recruitment of an unfished population obtained when the spawning stock biomass is 20% of its unfished level. We use a model of harvest-induced evolutionary change to understand how the steepness of the stock–recruitment relationship changes due to fishing. If the true spawning stock biomass is known, the stock–recruitment relationship changes little under fishing-induced evolution and there is little concern for fisheries management. When management is based on a total biomass – recruitment relationship, recruitment may be underestimated, which is also of little concern from a sustainability perspective. However, when the number of spawners – recruitment relationship is used to forecast recruitment, management practice that ignores the evolution of steepness may overestimate recruitment and therefore recommend catches that exceed safe biological limits. Using outdated maturity ogives underestimates spawning stock biomass, which results in steeper and higher stock–recruitment relationships as life histories evolve. Although of little concern for sustainability, this may pose challenges for practical fisheries management.

scholarly journals Harvesting juveniles of blackspot sea bream (Pagellus bogaraveo) in the Azores (Northeast Atlantic): biological implications, management, and life cycle considerations

2014 ◽  
Vol 71 (9) ◽  
pp. 2448-2456 ◽  
Author(s):  
Mário Pinho ◽  
Hugo Diogo ◽  
Joana Carvalho ◽  
João Gil Pereira
Keyword(s):  
Fork Length ◽  
Fishing Effort ◽  
Coastal Areas ◽  
Sea Bream ◽  
Ontogenetic Migration ◽  
Shelf Slope ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Pagellus Bogaraveo ◽  
Live Bait

Abstract Blackspot sea bream (Pagellus bogaraveo) is the most important economical resource of Azorean fisheries. Juveniles (age 0 and 1) were detected along island coastlines in nursery grounds that sheltered individuals of up to 13 cm (fork length). Juveniles occurred in coastal areas in all seasons, but higher catch per unit efforts occurred during summer. Larger individuals tended to be caught on the shelves and slopes of the islands and seamounts by the demersal, mixed hook, and line fisheries. Juveniles were exclusively found at inshore areas, while spawners were distributed over offshore areas (islands shelf/slope and seamounts), suggesting an inter-connected cycle of recruitment in coastal areas and ontogenetic migration of juveniles from inshore to offshore areas, while eggs and larvae drift in the opposite direction. Juveniles were found to be targeted by three types of fisheries, amounting to cumulative annual catches of ∼36 t. Shore angling was the most important fishing method, followed by bait fishing for tuna and the coastal pelagic live-bait fishery. Fishery managers have enforced several measures to protect juveniles, although our results indicate that effective interdiction of juvenile catch would provide a long-term increase of 15 and 8% in spawning-stock biomass and catch, respectively, as well as ∼13% increase in the value of landings. Although this measure could improve the protection of a species in an advanced state of overexploitation, our results showed that a decrease in fishing effort would be necessary to achieve sustainability of the stock.

scholarly journals Can fisheries-induced evolution shift reference points for fisheries management?

2013 ◽  
Vol 70 (4) ◽  
pp. 707-721 ◽  
Author(s):  
Mikko Heino ◽  
Loїc Baulier ◽  
David S. Boukal ◽  
Bruno Ernande ◽  
Fiona D. Johnston ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Fish Population ◽  
Reference Points ◽  
Population Characteristics ◽  
Biological Processes ◽  
Fishing Mortality ◽  
Intended Meaning ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Induced Changes

Abstract Heino, M., Baulier, L., Boukal, D. S., Ernande, B., Johnston, F. D., Mollet, F. M., Pardoe, H., Therkildsen, N. O., Uusi-Heikkilä, S., Vainikka, A., Arlinghaus, R., Dankel, D. J., Dunlop, E. S., Eikeset, A. M., Enberg, K., Engelhard G. H., Jørgensen, C., Laugen, A. T., Matsumura, S., Nusslé, S., Urbach, D., Whitlock, R., Rijnsdorp, A. D., and Dieckmann, U. 2013. Can fisheries-induced evolution shift reference points for fisheries management? – ICES Journal of Marine Science, 70: 707–721. Biological reference points are important tools for fisheries management. Reference points are not static, but may change when a population's environment or the population itself changes. Fisheries-induced evolution is one mechanism that can alter population characteristics, leading to “shifting” reference points by modifying the underlying biological processes or by changing the perception of a fishery system. The former causes changes in “true” reference points, whereas the latter is caused by changes in the yardsticks used to quantify a system's status. Unaccounted shifts of either kind imply that reference points gradually lose their intended meaning. This can lead to increased precaution, which is safe, but potentially costly. Shifts can also occur in more perilous directions, such that actual risks are greater than anticipated. Our qualitative analysis suggests that all commonly used reference points are susceptible to shifting through fisheries-induced evolution, including the limit and “precautionary” reference points for spawning-stock biomass, Blim and Bpa, and the target reference point for fishing mortality, F0.1. Our findings call for increased awareness of fisheries-induced changes and highlight the value of always basing reference points on adequately updated information, to capture all changes in the biological processes that drive fish population dynamics.

scholarly journals Spatial reference points for groundfish

2016 ◽  
Vol 73 (10) ◽  
pp. 2468-2478 ◽  
Author(s):  
Emilie Reuchlin-Hugenholtz ◽  
Nancy L. Shackell ◽  
Jeffrey A. Hutchings ◽  
Keyword(s):  
Fisheries Management ◽  
High Density ◽  
Reference Points ◽  
Spatial Reference ◽  
Individual Fitness ◽  
Fitness Consequences ◽  
Positive Individual ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Density Dependent Habitat Selection

Abstract According to density-dependent habitat selection theory, areas of high density can be indicative of high population productivity and have positive individual fitness consequences. Here, we explore six groundfish populations on the Scotian Shelf, Canada, where a decline in areas of high density beyond a certain threshold is associated with disproportionately large declines in Spawning Stock Biomass (SSB). This is evidenced by empirical, concave, positive relationships between high-density areas (HDAs) and SSB. We introduce a methodology to estimate the threshold below which SSB declines increasingly faster per unit of HDA decline. The spatial threshold among these six stocks was remarkably consistent; when stocks lose 70–80% of HDAs, disproportionately large SSB declines are likely to occur. We propose that spatial thresholds could serve as spatial reference points to complement existing SSB limit reference points (LRPs). For some stocks we identify spatial thresholds which correspond to SSB levels that exceed those associated with the designated SSB LRP, suggesting that a review of these SSB LRPs warrants merit. For other stocks, spatial reference points can be used in concert with SSB reference points, strengthening efforts to incorporate a precautionary approach to fisheries management. Our results warrant further research into the general application of HDA as spatial limit and target reference points for fisheries management in addition to other population status indicators within a broad recovery framework.

Maintenance of a Walleye, Stizostedion vitreum vitreum, Fishery in a Eutrophic Reservoir

1977 ◽  
Vol 34 (10) ◽  
pp. 1725-1733 ◽  
Author(s):  
Walter T. Momot ◽  
Jack Erickson ◽  
Frederick Stevenson
Keyword(s):  
Temperature Regime ◽  
Geographical Location ◽  
Maximum Growth ◽  
Gizzard Shad ◽  
Optimum Temperature ◽  
Poor Growth ◽  
Intensive Exploitation ◽  
Spawning Stock ◽  
Preferred Temperatures ◽  
Poor Recruitment

Hoover Reservoir, a very eutrophic environment, produces a successful fishery for walleye. However the population can only be sustained by stocking due to the absence of high quality summer habitat, intensive exploitation, poor recruitment of most natural year-classes, and poor growth of adult walleye. The oxygen temperature regime brought about by eutrophication forces the adult walleye to live at an above optimum temperature regime for maximum growth during the summer months. Because of the climate and geographical location, the preferred temperatures of the desired prey, young gizzard shad, are far above that of the adult walleye. This makes the shad less accessable to predation for a large portion of the day further reducing the growth of older walleye. Poor recruitment of large natural year-classes results from the absence of gizzard shad fry which spawn much later than walleye, at the time larval walleye convert from a planktonic to a piscivorous feeding habit. Large year-classes of walleye are produced in years when fry were stocked. Stocked fry were produced in hatcheries from spawn obtained at the reservoir. Fry were stocked in the reservoir just at or in advance of shad spawning, whereas in most years naturally produced fry appeared well in advance of shad spawning. This delayed appearance of stocked walleye fry probably accounts for their successful year-class production. This walleye spawning stock had an estimated mean biomass of 13.6 kg/ha and a mean annual production of 2.2 kg/ha between 1967 and 1973. Key words: Hoover Reservoir — Ohio, Percidae, Stizostedion, management, fry stocking

scholarly journals A two-stage biomass model to assess the English Channel cuttlefish (Sepia officinalis L.) stock

2014 ◽  
Vol 71 (9) ◽  
pp. 2457-2468 ◽  
Author(s):  
Michaël Gras ◽  
Beatriz A. Roel ◽  
Franck Coppin ◽  
Eric Foucher ◽  
Jean-Paul Robin
Keyword(s):  
Reference Points ◽  
Sea Surface ◽  
Sepia Officinalis ◽  
Sustainable Utilization ◽  
English Channel ◽  
Two Stage ◽  
Stock Biomass ◽  
Exploitation Rate ◽  
Spawning Stock ◽  
Age Structured

Abstract The English Channel cuttlefish (Sepia officinalis) is the most abundant cephalopod resource in the Northeast Atlantic and one of the three most valuable resources for English Channel fishers. Depletion methods and age-structured models have been used to assess the stock, though they have shown limitations related to the model assumptions and data demand. A two-stage biomass model is, therefore, proposed here using, as input data, four abundance indices derived from survey and commercial trawl data collected by Ifremer and Cefas. The model suggests great interannual variability in abundance during the 17 years of the period considered and a decreasing trend in recent years. Model results suggest that recruitment strength is independent of spawning–stock biomass, but appears to be influenced by environmental conditions such as sea surface temperature at the start of the life cycle. Trends in exploitation rate do not reveal evidence of overexploitation. Reference points are proposed and suggestions for management of the sustainable utilization of cuttlefish in the English Channel are advanced.

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