scholarly journals Evaluation of the effectiveness of marine reserves for transient spawning aggregations in data-limited situations

2013 ◽  
Vol 71 (3) ◽  
pp. 435-449 ◽  
Author(s):  
Arnaud Grüss ◽  
David M. Kaplan ◽  
Jan Robinson
Keyword(s):  
Marine Reserves ◽  
Fishing Effort ◽  
Spawning Aggregation ◽  
Management Options ◽  
Spawning Site ◽  
Spawning Aggregations ◽  
Stock Biomass ◽  
Fish Spawning ◽  
Spawning Stock ◽  
Effort Reduction

Abstract Many coral reef fish species form predictable, transient spawning aggregations. Many aggregations are overfished, making them a target for spatial management. Here, we develop a per-recruit model to evaluate the performance of no-take marine reserves protecting transient spawning aggregations. The model consists of only 14 demographic and exploitation-related parameters. We applied the model to a protogynous grouper and a gonochoristic rabbitfish from Seychelles and tested six scenarios regarding the extent of protected areas, the level of fish spawning-site fidelity, and fishing effort redistribution post reserve implementation. Spawning aggregation reserves improve spawning-stock biomass-per-recruit and reduce the sex ratio bias in protogynous populations for all scenarios examined. However, these benefits are often small and vary among the different scenarios and as a function of sexual ontogeny. In all scenarios, increases in yield-per-recruit do not occur or are negligible. The long-term yield increases due to spawning aggregation reserves may still occur, but only if spawning-stock biomass recovery results in a recruitment subsidy. Given these limited benefits, the value of no-take reserves must be weighed against those of other management options, such as fishing effort reduction and seasonal fishery closures. The latter is particularly appropriate when spawning and non-spawning areas overlap in space.

Effects of exploitation by two co-existing fleets on the bluefish, Pomatomus saltatrix, in southern Brazil: an application of a seasonal catch-at-age model

2002 ◽  
Vol 53 (5) ◽  
pp. 835 ◽  
Author(s):  
Flávia M. Lucena ◽  
Carl M. O'Brien ◽  
Enir G. Reis
Keyword(s):  
Southern Brazil ◽  
Pomatomus Saltatrix ◽  
Management Options ◽  
Time Period ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Age Model ◽  
Estimate Population Size ◽  
High Level ◽  
Seasonal Characteristic

This paper describes 20 years in the exploitation of the bluefish, Pomatomus saltatrix, in southern Brazil and investigates the effects of the commercial fleets on stock structure. Port samples were obtained from the commercial fisheries based at Rio Grande do Sul for the period 1992–1998. In addition, data derived from the exploitation during the period 1977–1983 (Krug and Haimovici 1991) were included in this analysis. A statistical catch-at-age model is proposed to estimate population size and exploitation rates for both periods of study. This model incorporates both the seasonal characteristic and multi-fleet nature of the P. saltatrix fishery. During the most recent time period, fishery mortality has increased and spawning stock biomass has reduced in comparison to the earlier period 1977–1983. Currently, the exploitation of P. saltatrix relies on fish of all age classes. Adults have been intensively exploited and juveniles may not be abundant enough to maintain the stock at the current high level of exploitation. Management options for the stock are presented based on a redistribution of effort between fleets. Simulations indicate that a ban on fishing in shallow waters for either one or both gears would restore the level of spawning stock biomass.

scholarly journals Management options for the Blackwater herring, a local spring-spawning stock in the Thames Estuary

2004 ◽  
Vol 61 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Beatriz A. Roel ◽  
Carl M. O'Brien ◽  
Marinelle Basson
Keyword(s):  
Fishing Effort ◽  
Current Approach ◽  
Slight Reduction ◽  
Trawl Survey ◽  
Management Options ◽  
Fishing Season ◽  
Thames Estuary ◽  
Spawning Stock ◽  
Management Advice ◽  
The Impact

Abstract Herring caught in the Thames Estuary sustain a small local commercial fishery (peak catch of 606 t during the 1972–1973 fishing season). Loss of local consumers' interest in the herring product has resulted in a gradual decline in catches and fishing effort for the stock. The stock is assessed using an age-structured model that relies on the information provided by a scientific trawl survey, and management advice is provided before the fishing season starts in October. Given its current low economic value, managers have requested evaluation of options for multi-annual Total Allowable Catches (TACs) in an attempt to reduce the frequency (and costs) of assessment and associated management advice. A tentative relationship between sea surface temperature and recruitment is used to predict the impact of increasing sea temperatures on future recruitment in the context of global warming. Hypotheses of auto-correlation and of an environmental effect on recruitment, together with trends in weight-at-age and the overestimation of spawning-stock biomass, form the basis for sensitivity tests of the management options considered. Implementation of a 3-year fixed TAC with 40% constraint in TAC variability and a slight reduction in target F would seem appropriate for the stock, given that it is within safe biological limits and compares well in terms of yield and risk with the current approach of annual TAC revision.

Status of exploited Baltic flounder stocks in the southern Baltic area (ICES SD 26)

2007 ◽  
Vol 36 (4) ◽  
Author(s):  
B. Draganik ◽  
S. Ivanow ◽  
Maciej Tomczak ◽  
B. Maksimov ◽  
I. Psuty-Lipska
Keyword(s):  
Good Condition ◽  
Fishing Effort ◽  
Current Status ◽  
Economic Changes ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Southern Baltic ◽  
The Baltic ◽  
High Level ◽  
Baltic Area

Status of exploited Baltic flounder stocks in the southern Baltic area (ICES SD 26)Flounder is the target of directed fisheries in coastal waters and is a bycatch of cod fishing. Flounder were fished in the Baltic region ICES Subdivision 26 (SD 26) by Polish and Soviet fleets until 1991. Since that time political and economic changes have altered the exploitation structure of that area, leading to increased fishing effort and flounder catches. This report, which is based on Polish, Russian and Lithuanian data, presents a review of long term changes in flounder fisheries in SD 26, and describes the current status of flounder exploitation there. The eXtended Survival Analysis (XSA) method was used to assess the stock. The results indicate that the flounder stock in SD 26 is in good condition and that the spawning stock biomass (SSB) is at a consistently high level. However, the estimated mean fishing mortality (F

scholarly journals An assessment of longnose trevally (Carangoides chrysophrys) (Cuvier, 1833) fishery in the Arabian Sea, Oman

2016 ◽  
Vol 21 ◽  
pp. 19
Author(s):  
Issam H. Al-Rasady ◽  
Anesh Govender
Keyword(s):  
Arabian Sea ◽  
Maximum Yield ◽  
Total Mortality ◽  
Fishing Effort ◽  
Fishing Mortality ◽  
North West ◽  
The North ◽  
Key Population ◽  
Stock Biomass ◽  
Spawning Stock

The Present study assessed the fishery state of longnose trevally (Carangoides chrysophrys) in the North West Arabian Sea. Key population parameters were estimated, and yield and spawning stock biomass per recruit analyses were conducted. The equation presented by Alagaraja (1984) for estimating natural mortality resulted in M = 0.29 year-1 and lead to the best estimate of longevity. Hence this value was used in the yield and spawning stock biomass per recruit analyses. The total mortality (Z) was estimated as 0.39 year-1, based on a catch curve analysis. Length-at- and age-at-50% captures were 38.21cm and 4 years respectively. The yield and spawning biomass per recruit analyses indicate that the current fishing mortality rate (Fcurr) was lower than the fishing mortality corresponding to the maximum yield per recruit (Fmax) and was also higher than the target reference point (F0.1) , suggesting that overfishing, currently, does not occur. However, any increase in the fishing effort in the future may lead to overfishing. 

Reproductive biology and behavior associated with a spawning aggregation of the yellowfin grouper Mycteroperca venenosa in the US Virgin Islands

2020 ◽  
Vol 96 (1) ◽  
pp. 31-56 ◽  
Author(s):  
Richard S Nemeth ◽  
Elizabeth Kadison ◽  
Nancy J Brown Peterson ◽  
Jeremiah Blondeau
Keyword(s):  
Full Moon ◽  
Gonadosomatic Index ◽  
Virgin Islands ◽  
Time Of Day ◽  
Spawning Aggregation ◽  
Us Virgin Islands ◽  
Spawning Site ◽  
Closed Area ◽  
Fish Spawning ◽  
Annual Population

The reproductive characteristics, movement patterns and courtship behaviors associated with a yellowfin grouper (Mycteroperca venenosa, Linnaeus, 1758) fish spawning aggregation (FSA) were assessed between 2004 and 2014. The FSA was located on the Grammanik Bank, a seasonally closed area on the edge of the Puerto Rico platform, south of St. Thomas, US Virgin Islands. Fish arrived at the FSA site around full moon and departed 10–12 days after full moon (dafm), during two or three consecutive months, from January to May each year. Males were significantly larger than females and preceded females at the spawning site. Courtship coloration and behaviors showed distinct patterns relative to lunar date and time of day. Spawning was observed for several days each month in 2008, 2009, 2011 and 2014, from 6 to 10 dafm. Female gonadosomatic index (GSI) values were highest from 4 to 7 dafm. Spawning, which began at sunset, consisted of 7 to 12 males following one female along the bottom before ascending 10–20 m, then "rushing" upward to release gametes. Histological analysis of ovaries indicated females spawned every 2–3 nights, although 11.6% were capable of spawning two consecutive nights. Total spawning population size of yellowfin grouper fluctuated from 600 to 1100 fish during the study period, but consistent annual population assessments using scuba were difficult to carry out due to ocean conditions. Based on size-frequency analysis and other metrics, the M. venenosa spawning population at the Grammanik bank appears to be stable at this time with existing regulations.

scholarly journals Biased stock assessment when using multiple, hardly overlapping, tuning series if fishing trends vary spatially

2009 ◽  
Vol 66 (10) ◽  
pp. 2272-2277 ◽  
Author(s):  
Sarah B. M. Kraak ◽  
Niels Daan ◽  
Martin A. Pastoors
Keyword(s):  
Stock Assessment ◽  
Fishing Effort ◽  
Assessment Procedure ◽  
Moderate Degree ◽  
Fishing Mortality ◽  
Stock Biomass ◽  
Spatial Coverage ◽  
Spawning Stock ◽  
Age Model ◽  
Biased Perception

Abstract Kraak, S. B. M., Daan, N., and Pastoors, M. A. 2009. Biased stock assessment when using multiple, hardly overlapping, tuning series if fishing trends vary spatially. – ICES Journal of Marine Science, 66: 2272–2277. Fishing-effort distributions are subject to change, for autonomous reasons and in response to management regulations. Ignoring such changes in a stock-assessment procedure may lead to a biased perception. We simulated a stock distributed over two regions with inter-regional migration and different trends in exploitation and tested the performance of extended survivors analysis (XSA) and a statistical catch-at-age model in terms of bias, when spatially restricted tuning series were applied. If we used a single tuning index that covered only the more heavily fished region, estimates of fishing mortality and spawning-stock biomass were seriously biased. If two tuning series each exclusively covering one region were used (without overlap but together covering the whole area), estimates were also biased. Surprisingly, a moderate degree of overlap of spatial coverage of the two tuning indices was sufficient to reduce bias of the XSA assessment substantially. However, performance was best when one tuning series covered the entire stock area.

scholarly journals Balancing conservation and utilization in spawning aggregation fisheries: a trade-off analysis of an overexploited marine fish

2019 ◽  
Vol 77 (1) ◽  
pp. 148-161
Author(s):  
Brad E Erisman ◽  
Arnaud Grüss ◽  
Ismael Mascareñas-Osorio ◽  
Hector Lícon-González ◽  
Andrew F Johnson ◽  
...  
Keyword(s):  
Marine Fish ◽  
Gulf Of California ◽  
Egg Production ◽  
Fishing Effort ◽  
Spawning Aggregations ◽  
Fish Spawning ◽  
Stakeholder Input ◽  
Sustainable Fishery ◽  
Yield Per Recruit

Abstract Although the management of fish spawning aggregations (FSAs) often requires a precautionary approach that initially emphasizes conservation, understanding the dynamics of spawning and interactions with fishing activities can help identify long-term management solutions that balance conservation with utilization. We designed a parsimonious, per-recruit model to evaluate the potential effects of seven time-closure scenarios implemented during the spawning season on egg production per recruit (EPR; a conservation metric) and yield per recruit (YPR; a fisheries metric) of Gulf corvina (Cynoscion othonopterus), a vulnerable marine fish that experiences persistent overfishing at its only known spawning grounds in the Gulf of California, Mexico. Three of the seven scenarios provided small-to-large increases in EPR (8–43%) accompanied by only small decreases in YPR (3–11%) that resulted in a sustainable fishery. Increased mortality of juveniles and small adults through targeted fishing or as bycatch in other fisheries, however, would erode the fisheries and conservation benefits of time closures. Our results demonstrate that information on spawning and fishing activities can be combined with stakeholder input to identify regulations that permit the sustainable harvesting of FSAs. Furthermore, the implementation of brief, temporal fishing effort restrictions can represent a viable, less restrictive alternative to marine protected areas for the management of FSAs.

scholarly journals Fish populations forming transient spawning aggregations: should spawners always be the targets of spatial protection efforts?

2014 ◽  
Vol 72 (2) ◽  
pp. 480-497 ◽  
Author(s):  
Arnaud Grüss ◽  
Jan Robinson
Keyword(s):  
Life History ◽  
Reef Fish ◽  
Life History Traits ◽  
Sensitivity Analyses ◽  
Substantial Fraction ◽  
Management Options ◽  
Spawning Aggregations ◽  
Fish Spawning ◽  
Spawning Sites

Abstract Many coral reef fish form transient spawning aggregations at sites located a few to hundreds of kilometres from their normal residence areas. Reef fish spawning aggregations (“FSAs”) are often heavily exploited, which make them targets for management with marine reserves. We used a per-recruit model to compare the long-term conservation (impacts on female spawning-stock biomass-per-recruit (SSBR) and female : male sex ratio, SR) and fisheries effects (impacts on yield-per-recruit, YPR) of spawning reserves vs. normal residence reserves for two data-poor populations from Seychelles with contrasting life history traits and sexual modes: the Siganus sutor population of the main granitic islands, which has a fast life history and is gonochoristic and the Epinephelus fuscoguttatus population of Farquhar Atoll, which has a slow life history and is protogynous. Overall, our results suggest that normal residence reserves are more effective at improving both the SSBR and YPR of S. sutor. In contrast, the protection of a substantial fraction of spawning sites is preferable for E. fuscoguttatus to ensure the reproductive output of this protogynous population through normalization of SR and maintenance of high SSBR. Neither spawning reserves nor normal residence reserves improved the YPR of E. fuscoguttatus. However, yields of E. fuscoguttatus may increase on the long term via recruitment subsidy if a substantial fraction of spawning sites is protected. This may occur only if the population was recruitment limited in the absence of reserves and increases in SSBR compensate for lost opportunities caused by the area closures. Sensitivity analyses revealed that the relative effects of spawning reserves and normal residence reserves relate more to the change in catchability occurring with FSA formation than to life history traits. Thus, normal residence reserves should be preferred over spawning reserves for S. sutor essentially because its catchability at spawning sites is low relative to many other aggregation-forming populations. S. sutor therefore suffers higher fishing mortality in normal residence areas than at FSA sites. Our study demonstrates that spawning reserves are not always the most effective tool for balancing conservation and exploitation objectives for FSA-forming populations, and that this measure should ideally be weighed against other management options.

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.

Optimal effort controls for the multispecies groundfish complex in New England: what might have been

2003 ◽  
Vol 60 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Daniel S Holland ◽  
Jean-Jacques Maguire
Keyword(s):  
New England ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Fishing Mortality ◽  
Alternative Control ◽  
Control Rules ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Age Structured ◽  
Groundfish Fishery

Age-structured models are used to calculate catches and revenues of the principal stocks in the northeast multispecies groundfish fishery over the 1982–1997 period assuming alternative control rules on fishing effort had been employed. Various static levels of nominal effort are compared with controls that maintain fishing mortality below overfishing thresholds for all stocks. An unambiguous result from this analysis is that substantial reductions in fishing effort would have increased the value of the fishery even if resulting increases in spawning stock biomass (SSB) had not increased recruitment. Simple controls on nominal effort designed to maximize revenues would have provided nearly equivalent revenues to those achieved by maintaining fishing mortality for each stock at its individual maximum sustainable yield (FMSY) but would have led to overfishing of some stocks. Without the ability to tune the relative catches across stocks, strict controls on effort designed to prevent overfishing on individual stocks would likely have resulted in significantly lower and more variable revenues. Achieving SSB targets for three stocks would not have been possible given the observed recruitment.

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