Use of a Multiplicative Model to Estimate Catch Rate and Effort from Commercial Data

1980 ◽  
Vol 37 (12) ◽  
pp. 2272-2275 ◽  
Author(s):  
Stratis Gavaris
Keyword(s):  
Stock Assessment ◽  
Multiplicative Model ◽  
Catch Rate ◽  
Total Catch

The multiplicative model described by Robson can be used to obtain estimates of annual standardized catch rate and its variance by including years in the model. The corresponding estimate of standardized effort is the ratio of the total catch and the estimated catch rate. If the error is assumed to be lognormally distributed then these estimators have well defined statistical properties.Key words: effort standardization, catch rate, multiplicative model, stock assessment

Stock assessment and risk analysis for the school shark (Galeorhinus galeus) off southern Australia

1998 ◽  
Vol 49 (7) ◽  
pp. 719 ◽  
Author(s):  
André E. Punt ◽  
Terence I. Walker
Keyword(s):  
Stock Assessment ◽  
Catch Rate ◽  
Data Series ◽  
Structured Population ◽  
Population Dynamics Model ◽  
Equilibrium Size ◽  
Structured Population Dynamics ◽  
Pup Survival ◽  
Galeorhinus Galeus ◽  
Selection Of

A spatially aggregated age- and sex-structured population dynamics model was fitted to standardized catch-rate data from the school shark resource off southern Australia. The model incorporates the peculiarities of shark populations and fisheries, including the pupping process and the selectivity characteristics of gill-nets. Estimates are determined by a Bayesian approach that incorporates prior distributions for virgin biomass, the parameter that determines productivity, and the variation in pup survival. Tests of sensitivity include changing the data series used, varying the value of adult natural mortality, and changing the prior distribution for the productivity parameter. The point estimates of the mature biomass at the start of 1995 range from 13% to 45% of the pre-exploitation equilibrium size, depending on the specifications of the assessment. The results are notably sensitive to the selection of a catch-rate series. Results suggest that the current fishing intensity will lead to further declines in abundance, that a reduction of ~20% in fishing mortality would achieve a 0.5 probability of not declining further, and that a reduction of 42% would achieve with a probability of 0.8 the management goal of not being below the 1996 mature biomass at the start of 2011. Extra keyword: CPUE.

Accounting for marine reserves using spatial stock assessments

2015 ◽  
Vol 72 (2) ◽  
pp. 262-280 ◽  
Author(s):  
Carey R. McGilliard ◽  
André E. Punt ◽  
Richard D. Methot ◽  
Ray Hilborn
Keyword(s):  
Spatial Heterogeneity ◽  
Stock Assessment ◽  
Marine Reserves ◽  
Movement Patterns ◽  
Catch Rate ◽  
Fish Stock ◽  
Rate Data ◽  
Stock Assessments ◽  
Age Structured ◽  
Movement Parameters

Some fish stock assessments are conducted in regions that contain no-take marine reserves (NTMRs). NTMRs are expected to lead to spatial heterogeneity in fish biomass by allowing a buildup of biomass inside their borders while fishing pressure occurs outside. Stock assessments do not typically account for spatial heterogeneity caused by NTMRs, which may lead to biased estimates of biomass. Simulation modeling is used to analyze the ability of several stock assessment configurations to estimate current biomass after the implementation of a single, large NTMR. Age-structured spatial operating models with three patterns of ontogenetic movement are used to represent the “true” population dynamics. Results show that assessing populations as a single stock with use of fishery catch-rate data and without accounting for the NTMR results in severe underestimation of biomass for two of the movement patterns. Omitting fishery catch-rate data or allowing time-varying dome-shaped selectivity after NTMR implementation leads to improved estimates of current biomass, but severe bias in estimated trends in biomass over time. Performing separate assessments for fished areas and NTMRs leads to improved estimation performance in the absence of movement among assessment areas, but can severely overestimate biomass otherwise. Performing a spatial assessment with estimation of movement parameters among areas was found to be the best way to assess a species, even when movement patterns were unknown. However, future work should explore the performance of spatial assessments when catchability varies among areas.

scholarly journals Effects of scallop dredging on macrobenthic communities in west Iceland

2006 ◽  
Vol 63 (3) ◽  
pp. 434-443 ◽  
Author(s):  
Elena Guijarro Garcia ◽  
Stefán Áki Ragnarsson ◽  
Hrafnkell Eiríksson
Keyword(s):  
Benthic Community ◽  
Stock Assessment ◽  
Benthic Communities ◽  
Fishing Effort ◽  
Early Years ◽  
Total Catch ◽  
Macrobenthic Communities ◽  
Modiolus Modiolus ◽  
Cucumaria Frondosa

Abstract Effects of scallop dredging on benthic communities in Breidafjordur, west Iceland, were investigated by analysing bycatch data from scallop stock assessment surveys and effort data from the commercial scallop fishery. Bycatch constituted 28% of the total catch, with eight benthic macrofaunal taxa alone making up nearly 98% of the bycatch. Modiolus modiolus and Cucumaria frondosa dominated in terms of abundance and biomass in most of the study area regardless of intensity of fishing effort, although both have been identified as sensitive to fishing in other studies. The macrofaunal benthic community in Breidafjordur consisted mostly of hard-shelled molluscs, holothurians, crabs, and starfish. Emerging epifauna was absent in the samples taken since 1993. These results suggest that our study was carried out within an already altered community that would have suffered the greatest impact during the early years of the scallop fishery. However, the available data are not enough to endorse this assumption with complete certainty.

scholarly journals An investigation into fisheries interaction effects using Atlantis

2014 ◽  
Vol 72 (1) ◽  
pp. 275-283 ◽  
Author(s):  
Michael D. Smith ◽  
Elizabeth A. Fulton ◽  
Robert W. Day
Keyword(s):  
Fisheries Management ◽  
Carrying Capacity ◽  
Stock Assessment ◽  
Single Species ◽  
Interaction Effects ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Simultaneous Increase ◽  
Total Catch ◽  
The Impact

Abstract Fisheries management is commonly based on the outputs of single-species stock assessment models. While such models are appropriate for tactical issues such as quota setting, they typically omit explicit trophic interactions between different parts of the ecosystem. To successfully manage multiple fisheries in the same ecosystem, we need to understand how fishing one species may indirectly affect other species. In this paper, we used a simulation model of the southern Benguela ecosystem, built in the Atlantis framework, to explore fisheries interaction effects. We first measured the impact of fishing different stocks individually at FMSY, the hypothetical level of fishing effort which produces maximum sustainable yield (MSY) in a single-species modelling context. We then applied FMSY to all stocks simultaneously and compared the simultaneous yield with the sum of yields from the individual applications of FMSY. Contrary to expectations, the total catch was higher under the simultaneous scenario. We explored our results by studying the influences of trophic interaction between species at different levels of the foodweb, and found that our overall result was driven by two key factors: volumetric dominance of small pelagic fish in the total catch, and asymmetric influences of competition and predation between piscivorous and planktivorous species. The simultaneous increase in fishing pressure across multiple species in the model led to increased effective carrying capacity for small pelagic species (due to reduced competition), but reduced carrying capacity for piscivorous species (due to reduced small pelagic prey). This work has important implications for the design of tactical multispecies models for use in ecosystem-based fisheries management.

scholarly journals Composition and catch rate of folded cube fish pots in the sea of Tuban Regency

2020 ◽  
Vol 147 ◽  
pp. 02003
Author(s):  
Adi Suhariyanto ◽  
Faizal Rachman ◽  
Eko Setyobudi ◽  
Riza Yuliratno Setiawan ◽  
Nahla Alfiatunnisa ◽  
...  
Keyword(s):  
Hermit Crab ◽  
Weighted Average ◽  
Catch Rate ◽  
Swimming Crab ◽  
Total Catch ◽  
Dominant Type ◽  
Fish Group ◽  
Average Catch

This study aimed to determine the composition and catch rate of folded cube fish pots in the seawater of the Tuban Regency. The research was conducted in December 2018 located in the Sokorejo, Tuban Regency, using 30 units of folded cube fish pots with a size of 50x50x50 cm2. The cube folded trap installation was done in 10 times of catch trip and installed in the morning. The catches were collected, identified, and measured for their individual length and weight. The crabs were measured for the length and width of their carapace. The catching result of folded cube fish pots was classified into five types which are fish group (48.97%), crabs group (29.59 %), swimmer crabs (7.1%), Land hermit crab (6.12%), and mud snails (8.16%). The result showed that Two-spined Arm Swimming Crab (Charybdis anisodon) was the most dominant type of catch equal to 29.59% of the total catch, while other types of catch that were quite common are Pig Faced Leather Jacket (Paramonacanthus choirocephalus) (9.18%), and Crescent Pearch (Terapon jarbua) (8.16%). The average catch rate for folding cube was 32%/trip with a weighted average catch of 436.58 gr/trip.

Relationship between settlement of southern rock lobster pueruli, Jasus edwardsii, and recruitment to the fishery in Tasmania, Australia

2001 ◽  
Vol 52 (8) ◽  
pp. 1271 ◽  
Author(s):  
C. Gardner ◽  
S. D. Frusher ◽  
R. B. Kennedy ◽  
A. Cawthorn
Keyword(s):  
Interannual Variation ◽  
Stock Assessment ◽  
Catch Rate ◽  
Assessment Model ◽  
Rock Lobster ◽  
Commercial Catch ◽  
Jasus Edwardsii ◽  
Catch Rates ◽  
Additional Support ◽  
Northeast Coast

Puerulus catches on artificial collectors were measured monthly at four sites around Tasmania from 1991 to April 2000, with the aim of predicting future changes in recruitment to the fishery. Support for the potential of catch-rate prediction in Tasmania was provided at the two sites that have overlap of several years between indices of puerulus settlement and indices of the abundance of recruits to the fishery. At Bicheno, on the northeast coast, correlations between annual puerulus index and commercial catch rates were highly significant, with a lag of 5 years (P< 0.01). Similar interannual trends in puerulus index and estimates from a stock-assessment model of the biomass of recruits to the fishery provided additional support for a link with puerulus index. A 5-fold interannual variation in puerulus index detected at Bicheno, with a peak in 1995, was preceded by 3 years of relatively low puerulus catch. The peak in puerulus index appears to lead to an increase in the abundance of sublegal males in research sampling 3 years later. Correlation between annual measures of puerulus index and catch rate also appeared significant at King Island (P= 0.06) although data at this site had less contrast.

scholarly journals Comparison of the Catching Results of Mini One-Boat and Two-Boat Purse Seine in Bali Strait, Muncar, East Java Province

2020 ◽  
Vol 5 (1) ◽  
pp. 8-14
Author(s):  
Yudi Nurul Ihsan ◽  
Nita Ulfah Khoirunisa ◽  
Indah Riyantini ◽  
Rahman Elfithri ◽  
Tri Dewi K. Pribadi ◽  
...  
Keyword(s):  
Fork Length ◽  
Operation Time ◽  
Catch Rate ◽  
Purse Seine ◽  
Primary Data ◽  
Fishing Gear ◽  
Total Catch ◽  
High Productivity ◽  
Schooling Fish ◽  
Catch Composition

Mini purse seine has a major contribution in increasing production of small pelagic catches in Pelabuhan Perikanan Pantai (PPP) Muncar, because it has high productivity and the construction made according to catch schooling fish. This research aims to compare the catches composition and catch rate of mini one-boat and two-boat purse seine in Bali Strait, Indonesia. This research was conducted in Mei 2018 in Muncar, East Java, Indonesia. The method used in this research is survey. The primary data are total catch composition, fork length, individual weight of total catch and operation time of both fishing gears. Data were analysed by main catch and bycatch proportion, legal size proportion and catch rate. The results showed that the mini two-boat purse seine had a greater catch volume compared to the mini one-boat purse seine. The bycatch composition dominates in both fishing gear. The proportion of legal-size catching is 67% of the total. The fork length is not significantly different and for the total catches is significantly different. The catching rate of the mini purse seine one boat catch rate is lower at 4,048.67 kg/hour, compared to the mini two-boat purse seine which is 9,189.18 kg/hour.

Optimum Size Limits for Trout Fisheries

1981 ◽  
Vol 38 (6) ◽  
pp. 657-661 ◽  
Author(s):  
A. L. Jensen
Keyword(s):  
Stock Assessment ◽  
Total Yield ◽  
Fishing Effort ◽  
Minimum Size ◽  
Total Catch ◽  
Optimum Size ◽  
A Value ◽  
Sport Fisheries ◽  
Size Limits ◽  
Very High

Application of conventional stock assessment methods to total catch of sport fisheries give neither optimum size limits nor optimum effort; as size limits decrease and effort increases total yield increases asymptotically. In this study total catch is separated into non-trophy and trophy catch; trophy catch has an optimum with respect to fishing effort. Increasing trophy catch decreases total catch, so to optimize the fishery a value is assigned to each category of catch. Optimum size limits for both conventional and slot limits are examined. A slot limit attempts to increase trophy catch without causing a substantial decrease in total catch. Fish are illegal until they reach some minimum size, then they are legal until they reach a certain size or age. They are then again illegal until they reach a trophy size. The results indicate recruitment age should be the smallest size acceptable to fishermen unless trophy fish have a very high value. With conventional size limits total catch decreases rapidly as age at entry increases and fishing effort decreases. Optimum slot limits are determined; slot limits produce a small increase in trophy catch and do not cause a large decrease in total catch.Key words: slot limits, trout fisheries, sport fisheries management, trophy catch

scholarly journals STATUS STOK, EKSPLOITASI DAN OPSI PENGELOLAAN SUMBERDAYA IKAN TUNA DI LAUT BANDA

2015 ◽  
Vol 7 (1) ◽  
pp. 45 ◽  
Author(s):  
Agustinus Anung Widodo ◽  
Ralph Thomas Mahulette ◽  
Fayakun Satria
Keyword(s):  
Stock Assessment ◽  
Purse Seine ◽  
Fishing Ground ◽  
Fishing Gear ◽  
Total Catch ◽  
Central Pacific ◽  
Central Pacific Ocean ◽  
Resource Sustainability ◽  
Tuna Fishing ◽  
Market Preference

<p>Laut Banda merupakan salah satu daerah penangkapan tuna yang potensial di Indonesia, Jenis alat tangkap yang digunakan terdiri dari pukat cincin, huhate, rawai tuna, pancing ulur dan pancing tonda. Hasil tangkapan tuna di Laut Banda meliputi cakalang, madidihang dan tuna mata besar. Sumberdaya tuna di Laut Banda diduga masih merupakan sub stok sumberdaya tuna di perairan Pasifik Tengah dan Barat. Hasil kajian stok tuna oleh Western and Central Pacific Fisheries Commission (WCPFC) pada 2012 melaporkan bahwa stok cakalang dan madidihang tidak mengalami overfishing dan overfished, sedangkan tuna mata besar telah mengalami overfishing dan overfished. Hasil penelitian Pusat Penelitian Pengelolaan Perikanan dan Konservasi Sumber Daya Ikan (P4KSI) pada 2012 menunjukkan madidihang dan tuna mata besar tertangkap pukat cincin, huhate serta kombinasi pancing ulur permukaan dan pancing tonda pada stadium yuwana, dengan indikasi nilai Lc&lt;Lm. Jumlah yuwana madidihang dan tuna mata besar yang tertangkap pukat cincin masing-masing mencapai sekitar 7,9 ton (26%) dan 1,5 ton (5%) dari rerata total hasil tangkapan sekitar 30,29 ton/kapal/trip. Jumlah yuwana madidihang dan tuna mata besar yang tertangkap huhate sekitar 0,71 ton (15%) dan 0,23 ton (5%) dari rerata total tangkapan sekitar 4,79 ton/kapal /trip. Jumlah yuwana madidihang dan tuna mata besar yang tertangkap pancing ulurpancing tonda sekitar 17% dan 2% dari rerata total tangkapan sebesar 0,31 ton/kapal/trip. Saat ini hasil tangkapan tuna yang berasal dari pukat cincin tidak dikehendaki pasar ekspor, mereka lebih memilih tuna hasil tangkapan huhate ataupun jenis pancing lainnya. Oleh karena itu salah satu kebijakan pengelolaan perikanan tuna di Laut Banda adalah tidak mengembangkan alat tangkap pukat cincin, adapun huhate, pancing ulur-pancing tonda masih tetap dapat dioperasikan.</p><p> </p><p>Banda sea is one of potential tuna fishing grounds among others in Indonesia. Various fishing gear types were operatedin this fishing ground such as pole &amp; line (PL), tuna long line (LL), hand line (HL) and troll line (TR). Skipjack (SKJ), yellowfin tuna (YFT) and bigeye tuna (BET) are main species caught in Banda sea and currently assumed as one stock in the Western Central Pacific Ocean (WCPO). Recent stock assessment done by WCPFC in 2012 reported that BET is in overfishing state (F&gt;Fmsy) while YFT and SKJ are not in overfishing or overfished state. It was also reported by RCFMC that the size of catch of those species by various fishing gear indicating that value of Lc&lt;Lm or in other word that catches are in juvenile stage. The juvenile YFT and BET caught by purse seine were considerably high for 7.9 t (26 %) and 1.5 t (5%) of the total catch 30.29 ton/vessel/trip. YFT and BET caught by pole and line are only 0.71 t (15%) and 0.23 t (5%) of the total catch 4.79 ton/vessel/trip. YFT and BET caught by hand line and troll line were only 17% and 2% of total catch 0.31 ton/vessel/trip. Considering the high pressure of purse seine to juvenile of tuna resource and market preference, so that to the best fishing practice for resource sustainability it is suggestted for tuna management in Banda sea should be not to develop and increase the effort for purse seine and may shift to pole line, hand line and/or troll line are still openated.</p>

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