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1.
The status of a fishery is often defined as the probability of fishing mortality rate exceeding a perilous level for long‐term sustainability. Lobster stock assessments are often subject to large uncertainty in input data and high levels of natural variability in lobster life history processes, which calls for incorporating uncertainty associated with both indicator and management reference points in an evaluation of biological risk of overfishing. Using a Monte Carlo simulation approach, we evaluated the impacts of uncertainty in modelling on the determination of the status of the Taitung spiny lobster (Panulirus penicillatus) fishery (Taiwan), which has not been quantitatively determined despite its commercial importance. The commonly used biological reference points derived from the per recruit model (F 0.1 the fishing mortality rate where the slope of the curve of yield‐per‐recruit model is 10% of the maximum slope and F 4Q%, the fishing mortality rate that reduces the expected egg production for a cohort of female lobsters to 40% of that produced in the absence of a fishery of the egg‐per‐recruit model) were influenced by uncertainties associated with lobster life history and fishery parameters. A large uncertainty in the current fishing mortality rate (F cnr) and estimates of biological reference points (F BRPs) increased the uncertainty in determining the risk of overexploitation throughout the confidence levels of the stochastic decision‐making framework. This simulation study suggests that the target reference point of F 40% is less sensitive to the input parameters’ uncertainty than F 0.1 We suggest a further evaluation of other F‐based references points and development of biomass‐based reference points before final selection and implementation for the management of the Taitung lobster fishery. 相似文献
2.
The shared Torres Strait rock lobster (Panulirus ornatus) fishery provides important income for commercial and traditional fishers in Australia and Papua New Guinea. The lobster stock is first fished in Torres Strait by divers from both countries and then becomes vulnerable to Australian prawn trawlers, followed by Papua New Guinea trawlers during its annual breeding migration. Lobster catch sharing arrangements are governed by the Torres Strait Treaty ratified in 1985, but the sequential trawling of breeding lobsters has been controlled by bilateral agreements. A trawl ban was implemented in 1984 in both countries to conserve the breeding stock, but some trawling has been conducted in the Gulf of Papua since then and there is renewed interest in Papua New Guinea to resume trawling. To evaluate the impact of trawling migratory breeding lobsters on the lobster fishery, a model that combines a cohort depletion model with a stock recruitment relationship was developed in this study. The model showed that when the fishery is fully or over‐exploited by the dive fishery, trawling breeding lobsters would reduce both the spawning stock and the total catch of the fishery. The reduction in catch would increase with increasing fishing mortality. If trawling occurred on the Papua New Guinea side only, a redistribution of catch between Australia and Papua New Guinea would result in a small gain in catch for Papua New Guinea at the expense of the Australian dive fishery. But when fishing mortality reaches a certain level, any trawling in any country will incur catch loss to both countries. For the long‐term sustainability and maximum production of the fishery, regulations should be implemented in both countries under a co‐management scheme of a shared fish stock. 相似文献
3.
The California spiny or red rock lobster, Panulirus interruptus, is an ecologically and economically important species that has been exploited since the 1800s. No previous study in California has assessed the impacts of the recreational or commercial lobster harvest. Before the 2003–04 commercial and recreational lobster seasons, we conducted a fishery‐independent trap survey at Santa Catalina Island to document the impact of the lobster fisheries on the size structure, abundance, and sex ratios of mature P. interruptus (>65 mm carapace length (CL)). We concurrently sampled a predominantly commercially fished area, a recreationally fished area, and a 23‐year‐old invertebrate no‐take (INT) reserve. Relative to the INT reserve, legal‐size lobsters in the recreational area were similar in CL, but 31% less abundant. Legal‐size lobsters in the commercial area were 8% smaller and 70% less abundant than those in the INT reserve. The sex ratio of legal‐size lobsters, although near 50:50 in the recreational and INT reserve areas, was male‐dominated (67:33) in the commercial area. Differences in CPUE and mean CL of sub‐legal lobsters in the recreational and commercial areas suggest that factors in addition to harvesting pressure may affect these populations. Total biomass of mature lobsters in the recreational and commercial areas was 92% and 45%, respectively, of biomass in the INT reserve. Fecundity in the recreational and commercial areas was 83% and 42%, respectively, of fecundity in the INT reserve. This study provides preliminary data for future ecological studies and fisheries management evaluations. 相似文献
4.
In Florida, United States, the Caribbean spiny lobster, Panulirus argus, supports an important commercial fishery and also perhaps the most intensive recreational fishery of any lobster species, with sales of recreational lobster fishing permits exceeding 100 000 annually. For the past decade, we have used mail surveys of recreational lobster license holders to estimate spatially explicit landings and fishing effort when recreational fishers are most active—during the state's “Special Two‐Day Sport Season”, which takes place just before the opening of the commercial season, and during the first month of the regular recreational season, which coincides with the commercial season. From 1993 through 2002, fishing effort during the Special Two‐Day Sport Season has ranged from 60 000 to 112 000 person‐days, and landings have ranged from c. 112 to 255t. Both fishing effort and landings have varied without trend. Fishing effort during the regular season over the same period has ranged from 261 000 to 514 000 person‐days, and landings have ranged from 434 to 825 t. Fishing effort has shown a marginally statistically significant decreasing trend, the result of a progressive decrease in effort since 1999. The largest proportion of both fishing effort and landings was concentrated along the south‐east coast. Despite the recent decrease in landings, the proportion of total landings made by the recreational fishery has increased. From 1993 through 1998, the fishery was responsible for c. 30% of commercial landings; by 2001, that percentage increased to nearly 40%. Such a shift in landings away from the commercial trap fishery toward the recreational fishery was recognised as a potential but unintended effect of the ongoing management plan of restricting effort in the commercial trap fishery. Our 2001 surveys revealed that recreational lobster fishers spent more on a person‐day basis than the general visitor to the Florida Keys did, but less than those visitors using the region's coral reefs. Consequently, managers must establish management strategies that allow the coexistence of this resource's user groups and also incorporate the social and environmental concerns of nonuser groups. 相似文献
5.
The western rock lobster fishery is one of the most valuable single‐species fisheries in Australia, valued at AU$300 million per year. The impact of environmental factors such as lunar cycle and swell on the daily catch rate of the western rock lobster (Panulirus cynus) is of particular interest in the stock assessment and management of the fishery. The variation in daily catch rates was examined for two periods (migrating period November‐January, non‐migrating period February‐June), at different depths in three management zones for three categories of lobster (undersize, legal size, and setose). Regression and transfer function models for relationships between catch rates and environmental data were considered and compared. The lunar cycle has a significant impact on the daily catch rates with c. 30% lower catch rate during the full moon and c. 20% higher catches near the new moon. This impact occurs mainly during the non‐migrating period both in deep water (40–100 m) and shallow water (<40 m). The swell on the day before fishing was also shown to be significantly related to the catch rate with an increase of c. 10–15% for an increase in swell from light to moderate or moderate to high. These environmental factors can be used to standardise catch rates to provide an improved abundance index for stock assessment. Also, management closures are being considered for 3–5 days over the low catch rate, full moon period to reduce fishing costs and lower fishing effort. 相似文献
6.
Southern rock lobster (Jasus edwardsii) support significant commercial and recreational fisheries in Tasmania, Australia. Since the mid 1990s the number of persons holding recreational lobster licences increased by over 80%, with c. 15 500 persons licensed in 2002/03. Assessment of the recreational fishery has been undertaken periodically since 1996 using a telephone‐diary survey method. The fishery was concentrated off the south‐east and east coasts of Tasmania and characterised by strong seasonality in catch and effort, which peaked markedly early in the fishing year (November‐January). Although pots were the most popular fishing method, daily catch rates by divers were more than double those for pots. Divers selectively harvested larger lobsters than those taken by pots and more frequently attained the daily bag limit of 5 lobsters. The estimated recreational harvest increased significantly since 1996/97 and in 2002/03 effectively reached a management trigger level of 10% of the total allowable commercial catch, flagging a review of recreational management arrangements. 相似文献
7.
E.V. Radhakrishnan V.D. Deshmukh Mary K. Manisseri M. Rajamani Joe K. Kizhakudan R. Thangaraja 《新西兰海洋与淡水研究杂志》2013,47(3):723-732
Commercial exploitation of lobsters from the Indian seas began in the 1950s. Annual landings have been declining from a peak of 4075 t in 1985 to 1364 t in 2002. Major fisheries were located on the north‐west, south‐west, and south‐east coasts. Among the 12 species recorded, only four species of spiny lobsters (three littoral and one deep sea) and one species of slipper lobster are commercially important. At Kayalpattinam and Tharuvaikulam, on the south‐east coast, lobster landings sharply declined for the gill‐net fishery. Of the two species that contributed to the fishery, Panulirus ornatus and Panulirus homarus, the latter has been more affected owing to high vulnerability to fishing activities. Catch composition analysis of the trammel‐net fishery showed that 35% of the landings consisted of P. homarus in the size range of 23–50 mm carapace length. On the north‐west coast, the spiny lobster Panulirus polyphagus and the slipper lobster Thenus orientalis are incidentally caught in trawl nets. However, the fishery for T. orientalis in the waters off Mumbai lasted only up to 1994. Large‐scale exploitation of spawning females, which formed 60% of the total catch, might have been detrimental to the recruitment process resulting in rapid decline and total collapse of the fishery. Abundance of P. polyphagus reached its maximum during September, constituting 23% of the average annual landing during 1988–2002. A high exploitation ratio (>0.7) indicated over‐fishing of the stock. Repeated spawning and high annual egg production are probably responsible for sustaining the stock, despite over‐exploitation. Major problems confronting the resource management of the multi‐gear and multi‐species lobster fisheries in India are discussed. An operational project, involving fisher community, has been taken up for creating awareness of the need for sustainable exploitation of the resource. Regulatory measures, such as closure of the fishery during the peak of the breeding season, ban on trammel‐net, mandatory release of egg‐bearing lobsters, and establishment of lobster sanctuaries are suggested to the State Governments for implementation. 相似文献
8.
Puerulus settlement has been monitored throughout the western rock lobster Panulirus cygnus fishery for nearly 40 years. These data, in combination with indices of effort and water temperature, were used to produce recruitment‐catch relationships for each 1° transect of latitude in the coastal part of this fishery from Kalbarri to Cape Leeuwin, as well as at the offshore Abrolhos Islands (total of eight transects). The fine spatial scales of these models provided estimates of certain life history traits that are known to affect lobster catches between adjacent fishing ports. This catch modelling showed that the proportions of 3‐ and 4‐year‐old post‐settlement lobsters contributing to the catches varied markedly from the southern to northern transects, suggesting that juvenile lobsters grow substantially faster in the warmer northern and offshore waters of this fishery. These proportions provide accurate estimates of juvenile growth rates, which are vital in the construction of location‐specific growth algorithms required by the age‐structured models used in the management of this fishery. Model estimates of density‐dependent mortality were greater in the more densely populated centre of the fishery and markedly lower at the northern and southern limits of this species distribution. Annual increases in fishing efficiency were also found to be lowest at the northern and southern extremes of the fishery and greatest in the centre of the fishery, where technology advances and increased fleet mobility have enabled the fleet to increase efficiency by 1–3% each year. Catchability (q) was found to be most influenced by water temperatures in the cooler southern transects, whereas at the Abrolhos Islands, changes in water temperature produced almost no discernable change in q. The catch modelling was also used to quantify the impact of management changes introduced in the 1993/94 fishing season. Increased protection of female lobsters and an 18% pot reduction resulted in a 3–4% permanent reduction in the catch rates of lobsters throughout most of the coastal fishery, whereas at the offshore Abrolhos Islands, catch rates increased by c. 20%, presumably owing to a reduction in the level of pot saturation. 相似文献
9.
The management strategy evaluation (MSE) approach was used to evaluate management strategies based on the current method of stock assessment for rock lobster (Jasus edwardsii) off Victoria, Australia, and decision rules inferred from the management plan for Victorian rock lobster and past practice when selecting total allowable catches, TACs. The results are expressed in terms of whether it is possible to keep stocks above limit reference points with high probability and recover over‐exploited stocks to the target level. Three categories of management strategy were examined using the MSE, which differed in whether assessments were conducted, and TACs set, by management zone or by region within management zone. A management strategy based on conducting assessments and setting TACs by management zone is most similar to the way assessments are currently conducted and management regulations implemented for rock lobster off Victoria. However, this management strategy performed poorest in recovering stocks to target levels. Alternative management strategies which involved conducting assessments and setting TACs by region performed better, but may have practical limitations. The assessment method was found to be generally relatively accurate and precise, although estimation performance was poor/imprecise on occasion. 相似文献
10.
One of the aims of Mediterranean marine protected areas (MPAs) is to increase populations of exploited species, such as the European spiny lobster (Palinurus elephas), which is considered a key species for its commercial and ecological value. Monitoring of temporal patterns in abundance of early benthic stages of P. elephas indicated that predation may be higher inside the Medes Islands MPA relative to adjacent control sites. Tethering experiments were performed to test whether predation rates actually differed within and outside the MPA. Relative mortality of recently‐settled juveniles inside the MPA was much higher than in control sites in adjacent non‐protected areas. Treatments with and without shelter indicated that predation on recently‐settled juvenile spiny lobsters was moderated by the availability of suitable shelter. The decline or absence of fish predators in the fished area may be the reason why juvenile lobsters outside the MPA experience lower predation than within the MPA. 相似文献
11.
Stock assessments based on fitting sex‐and size‐structured population dynamics models, combined with projections of the future implications for available biomass and egg production, currently form the basis for scientific management advice for rock lobster, Jasus edwardsii, off Victoria, Australia. Traditionally, assessments have been conducted for two “zones” (east and west) off Victoria. However, recent analyses indicate finer‐scale spatial resolution in growth and the probability of being mature as a function of size. Assessments were therefore conducted for six regions, as well as for the two conventional zones, and Bayesian model selection criteria were used to compare alternative model formulations. The results suggest that better fits to the data can be obtained by conducting assessments by region than by zone. The general qualitative conclusion of past stock assessments is that the rock lobster populations off Victoria are depleted to below the target reference point of 40% of the available biomass in 1951 and this conclusion is robust to how the data are treated spatially. However, the time‐trajectories of egg production and available biomass differ among the regions, with the areas in the centre of Victoria being more depleted than those at the extremes. 相似文献
12.
The Northern Zone rock lobster fishery of South Australia is expansive, covering an area of ∼207,000 km2. From 1970 to 2002 it was managed under input controls that relied heavily on restrictions to days-at-sea and size limits. In 2003, output controls in the form of individual transferable quotas with a total allowable commercial catch were also introduced. Fishery performance from 1980 to 2007 was analysed based on catch data and model outputs. Trends in catch and effort increased through the 1980s and 1990s while nominal catch rate remained relatively stable. However, from 1999 to 2003 catch decreased by 49% from 1001 to 503 ton and has remained at <500 ton since. Importantly, nominal effort did not decline comparatively, decreasing by only 12% from 1999 to 2007. Consequently, nominal catch rate decreased by 47.5% from 1.43 to 0.75 kg/potlift, over the same period. Logbook data revealed strong evidence of spatial expansion through the 1980s and 1990s which is likely to have masked declining lobster abundance and contributed to a “hyperstability” scenario in catch rates. It is suggested that increasing effective effort, driven by advances in fishing technology and vessel design, fuelled this expansion. Model outputs, which account for increases in effective effort, indicate that biomass has decreased by ∼68% since the 1980s. The results highlight the limitations associated with input controls in controlling effort during periods of spatial expansion. Further evidence from puerulus settlement data stresses the importance of conservative quotas for lobster fisheries where annual recruitment is low or highly sporadic. 相似文献
13.
ABSTRACT Movement patterns of the Southern Rock Lobster Jasus edwardsii in Victoria, Australia were investigated from 8,533 tag-recapture events across a 20-year period (1992–2012). In total, 83% of lobsters were recaptured within 1?km of their tagging site and 93% within 5?km. While largely resident, elevated movements were observed within specific regions, with the overall direction of movement being from inshore to offshore areas. Movement was not impacted by lobster sex, size, or reproductive stage. The fishery for Southern Rock Lobster within Victoria is currently managed into two zones with separate total allowable commercial catches in each area. Given the high levels of site fidelity, our findings suggest that management of the resource at this spatial scale is appropriate and that consideration of significant movement between zones is not warranted in fishery stock assessment models. 相似文献
14.
《Ocean & Coastal Management》2006,49(5-6):298-307
In 1999 the Marine and Marine Industries Council was established by the Tasmanian (Australia) State Government and in 2001 a Tasmanian Marine Protected Area Strategy was launched. The aims of this paper are to: investigate the views, perceptions and attitudes of commercial fishers towards this Strategy and to identify the key issues that influence fisher support or opposition to marine protected areas (MPAs). Fifty-one structured interviews with license supervisors of commercial abalone, rock lobster and scalefish fishers were conducted. Fishers stated that they would conditionally support MPAs if they sustained or increased fish populations, supported research, allowed fishing in multiple use areas, and if multiple use areas contained small ‘no-take’ zones. Fishers were concerned about the ability of the government to provide adequate marine protected area monitoring and compliance and were critical of the public consultation process that accompanied the development of the Strategy. Concern was expressed regarding the potential negative impact of additional MPAs in terms of resource sustainability and the long-term economic viability of the fishery. 相似文献
15.
We describe the development and application of a management procedure (decision rule) that resulted in a voluntary reduction in the commercial catch of spiny rock lobster (Jasus edwardsii) in the lower east coast of North Island of New Zealand. The management procedure was developed from an accepted assessment of the CRA 4 (Wellington‐Hawke's Bay) fishery, which used an integrated length‐based assessment model fitted to commercial fishery catch‐per‐unit‐effort (CPUE) biomass indices, commercial length‐frequency data, and tag‐recapture data. The assessment model had been Bayesian, and used the joint posterior distribution of parameters to predict the effect of 384 alternative harvest control rules on the future size of the CRA 4 stock. The harvest control rules all used CPUE as their input, and generated annual changes in catch, which were then simulated by the population dynamics of the operating model. Uncertainty was added to evaluations through observation error, added to the simulated CPUE observations, and stochastic serial auto‐correlation variation in recruitment. We describe how this management procedure was used to effect a voluntary reduction in catch to address the problem of a rapidly declining population. 相似文献
16.
The commercial fishery for Jasus lalandii, the South Africa West Coast rock lobster, began in the late 1800s and at its peak in the early 1950s yielded an annual catch of 18 000 t. Although this annual catch has dropped to only some 2000 t over recent years, the fishery remains South Africa's third most valuable for landed value. The primary reason for the low total allowable catch (TAC) over these recent years has been a marked drop in somatic growth rate that occurred at the end of the 1980s, for reasons that remain unexplained. A key problem in formulating TAC recommendations with longer‐term objectives in mind, has been uncertainties about likely future trends, particularly in somatic growth and recruitment. To address this problem, an “operational management procedure” (OMP) was adopted in 1997 and has twice been re‐evaluated and modified (in 2000 and 2003) in the light of further data and changing perceptions of resource dynamics. The history of this process is reviewed, concentrating on the most recent modification. In particular, a summary is given of the process by which the merits of alternative management procedures were evaluated over a range of important uncertainties about the dynamics of the resource. This summary includes a discussion of the key trade‐offs between resource rebuilding, future TAC trends and TAC variability, and the eventual choice that was made. The paper concludes by listing a number of lessons learnt concerning best practice for OMP development as this process evolved. 相似文献
17.
The southern rock lobster, Jasus edwardsii, is South Australia's most valuable fisheries resource, with an annual landed value of c. AU$100 million. Approximately 80% of this revenue comes from the southern zone (SZ) rock lobster fishery, which has been managed under an individual transferable quota system since 1993. The total allowable commercial catch is currently set at 1900 tonnes. Long‐term spatial trends in catch and effort were analysed over the period 1970–2005 to investigate possible changes in the spatial dynamics of the fleets as a result of quota introduction. Data indicate that the fishery contracted into three main Marine Fishing Areas (MFAs) after 1993. In particular, the long‐term catch average in MFA 51 decreased from 185.4 tonnes pre‐quota to 59.8 tonnes post quota. This MFA is located in the northern region of the SZ and is one of the furthest MFAs from the main fishing ports in the region. The fishery is also spatially contracted within MFAs. Approximately 80% of the annual catch comes from <60m depth despite catch rates being 2–3 times greater in offshore sites as evidenced from both fishery‐dependent and independent sources. Such trends appear driven by recent market preferences that select for small (<1 kg), red‐coloured lobster that are primarily located on inshore grounds. As a result, fishers now target inshore sites to maximise returns under the quota‐based system. The observed shift in the spatial dynamics of the SZ has clear implications for the biological performance indicators on which the fishery is managed. Specifically, the results highlight the need for a fishery‐independent assessment of the resource that provides estimates of catch rate and biomass independent of current harvest strategies. Preliminary results from a trial survey undertaken in 2005/06 and 2006/07 show higher lobster abundance in lowly exploited offshore sites compared with inshore areas. These trends highlight the need for refined spatial management of the resource, which is the focus of the new management plan for the fishery. 相似文献
18.
Neil Stump 《新西兰海洋与淡水研究杂志》2013,47(3):765-774
Plans by government to accelerate the establishment of a national representative system of marine protected areas (NRSMPAs) in Australia have caused increasing disquiet within the fishing industry. Rock lobster fishers have raised concerns regarding plans to establish large “multiple‐use” MPAs that may or may not contain a substantial no‐take component in the continental shelf waters adjacent to the coast. Key industry concerns including the potential impacts on present and future harvest rates are examined. The industry response to government MPA policy in each of the major jurisdictions is outlined. An industry position developed at the National Rock Lobster Congress in Perth, Western Australia (September 2003) is put forward. The position advocates the need for an adjustment scheme to account for displaced effort, the need for government commitment to the development of management plans that include the long‐term monitoring of all MPAs, and the need for a thorough risk assessment process to be conducted before the establishment of an MPA. The issues raised in this paper should be relevant to the establishment of MPAs in an international context. 相似文献
19.
Craig B. Kensler 《新西兰海洋与淡水研究杂志》2013,47(4):506-517
The spiny lobster Jasus edwardsii (Hutton) supports a thriving new fishery at the Chatham Islands, about 770 km east of New Zealand. Commercial fishing for J. edwardsii started in November 1965, and within 2 years the area became a major centre of New Zealand's large spiny lobster fishery, which earned >NZ$5,000,000 in 1967. Over 12 months (September 1966 to August 1967) landings at the Chatham Islands made up 39.8% of the total New Zealand spiny lobster catch of 16,600,0001b. In the first year of fishing 2,177,923 lb of spiny lobsters were caught, and in the second 7,129,658lb—a 227% increase. Fishing effort also increased substantially: average number of boats fishing each month rose by 174% in the second year, and the total number of boat‐fishing days by 152%. Most specimens of J. edwardsii caught are large and mature, typical of a virgin stock. 相似文献
20.
Any attempt to enhance rock lobster production by increasing survival after settlement, or by ongrowing or outplanting young juveniles, requires knowledge of the shelter preferences of young juveniles. For juvenile Jasus edwardsii in the wild these are not well known. Information available suggests that juveniles up to c. 35 mm carapace length (CL) occupy shelters that generally conform closely to their body dimensions but that larger juveniles use shelters of more variable dimension, often much larger than their body size. We investigated mainly physical factors important in shelter choice by 15–59 mm CL (c. 2–24‐month‐old juveniles) in laboratory tank experiments. In overnight tests, all sizes of juvenile lobster chose to occupy holes (shelters with sides) over open horizontal gaps. Preference for open horizontal gaps versus horizontal crevices (where the height reduces from a maximum at the mouth to zero at the opposite end) was much less clear‐cut; choice varied according to lobster size. For the number of entrances into holes, there was evidence for an ontogenetic shift in preference, small lobsters preferring two openings over one, whereas those >30 mm CL (c. 9 months old) preferred one over two. For lobsters <40 mm CL, the hole size and gap size preferences revealed were generally consistent with the field evidence for J. edwardsii in that there was a close and proportional relationship between lobster size and shelter size; what differed was that the open gaps chosen in the tanks by the smallest lobsters (15–19 mm CL) were larger than the holes used in the tank experiments and 30–50% larger than those reportedly used in the field. For lobsters >40 mm CL, the holes and gaps chosen in the tanks were generally larger and more variable in size, as in the field. 相似文献