Manual of Methods for Fish Stock Assessment. Part I. Fish Population Analysis.

1971 ◽  
Vol 8 (2) ◽  
pp. 616
Author(s):  
B. B. Parrish ◽  
J. A. Gullard
Keyword(s):  
Stock Assessment ◽  
Population Analysis ◽  
Fish Population ◽  
Fish Stock ◽  
Fish Stock Assessment

Sensitivities and Variances of Virtual Population Analysis As Applied to the Mackerel, Scomber japonicus

1988 ◽  
Vol 45 (3) ◽  
pp. 539-547 ◽  
Author(s):  
Michael H. Prager ◽  
Alec D. MacCall
Keyword(s):  
Stock Assessment ◽  
Population Analysis ◽  
Error Variance ◽  
Quantitative Model ◽  
Fish Stock ◽  
Scomber Japonicus ◽  
Virtual Population Analysis ◽  
Virtual Population ◽  
Coefficients Of Variation ◽  
Fish Stock Assessment

Virtual population analysis (VPA) is widely used in fish stock assessment. However, VPA results are generally presented as point estimates, without error variance. Using numerical methods, we estimated the total variance of historical (1929–65) biomass estimates of mackerel, Scomber japonicus, off southern California. In the years before 1940, coefficients of variation (CV's) approached 100%; later, when weights at age and the age structure of the catch were better known, the CV's were about 25%. Most of the variability derives from uncertainties in estimates of natural mortality (M) and of weights at age. We also developed dimensionless coefficients (sensitivities) to examine the effects of errors in the inputs on the VPA biomass estimates. The largest sensitivities were to M and the total catch and varied substantially from year to year. As expected, sensitivity to M decreased with increasing exploitation, and sensitivity to catch increased with increasing exploitation. Using such sensitivities, one could estimate the error in a biomass estimate for a past year when M (or any other input) was thought to be unusually high or low. Thus, retrospective corrections can be made. Also, such sensitivities form an analytic tool for examining the properties of VPA, or any quantitative model.

Detecting and correcting underreported catches in fish stock assessment: trial of a new method

2010 ◽  
Vol 67 (8) ◽  
pp. 1247-1261 ◽  
Author(s):  
Nicolas Bousquet ◽  
Noel Cadigan ◽  
Thierry Duchesne ◽  
Louis-Paul Rivest
Keyword(s):  
Gadus Morhua ◽  
Stock Assessment ◽  
Population Analysis ◽  
Assessment Model ◽  
Fish Stock ◽  
Stock Biomass ◽  
Stock Assessments ◽  
Spawning Stock ◽  
Age Structured ◽  
Fish Stock Assessment

Landings from fisheries are often underreported, that is, the true landings are greater than those reported. Despite this bias, reported landings are widely used in fish stock assessments, and this might lead to overoptimistic exploitation strategies. We construct a statistical stock assessment model that accounts for underreported landings using the theory of censoring with sequential population analysis (SPA). The new model is developed and implemented specifically for the cod stock ( Gadus morhua ) from the southern Gulf of St. Lawrence (Canada). This stock is known to have unreported overfishing during 1985–1992. We show in simulations that for this stock, the new censored model can correctly detect the problematic landings. These corrections are nearly insensitive to subjective boundaries placed on real catches and robust to modifications imposed in the simulation of landings. However, when surveys are too noisy, the new SPA for censored catches can result in increased uncertainty in parameters used for management such as spawning stock biomass and age-structured stock size.

scholarly journals BIOLOGICAL DIVERSITY ON THE BENINESE CONTINENTAL SHELF DURING THE DEMERSAL FISH STOCK ASSESSMENT SURVEY

2018 ◽  
pp. 48-59
Author(s):  
Sohou Zacharie ◽  
Okpeitcha O. Victor ◽  
Sankare Yacouba
Keyword(s):  
Biological Diversity ◽  
Stock Assessment ◽  
Demersal Fish ◽  
Fish Population ◽  
Species Number ◽  
Fish Stock ◽  
Survey Period ◽  
Continental Shelves ◽  
Assessment Survey ◽  
Fish Stock Assessment

The global objectives of this study are to assess biodiversity composition in the tested trawling areas during the survey period. This study cannot take in account all species that can occur in the fishing areas because of the shortness of the work. To have a most complete list of species it will be better to carry out the survey covering four hydrologic periods (2 hot and 2 cold hydrologic periods) to have a chance to meet most of the species. However, the work was done during the most important period for the study. This study was conducted in terms of the demersal fish stock assessment survey initiated by the West African Economic and Monetary Union in the continental shelves of states members and neighboring countries (Côte d'Ivoire, Ghana, Togo and Benin) for the south part of Africa in order to determine fish population and abundance. In the waters of Benin, there have been listed 100 fish species including 76 demersal species (69 bony and 7 cartilaginous fish) and 13 pelagic species consisting entirely of bony specimens. Species richness, according to the reports of trawling stations, varies between 28 and 7 species. Fish abundance is the largest at the depth of 25-50 m. According to the data of station 10, species number makes 7.76% of the total, followed by station 19 with 26 taxa at the depth of 50-100 m. The lowest taxon number is registered in station 4 at a depth of 10-25 m with 4 taxa representing 1.94% of all targeted. The Simpson's index is close to 0, varying between 0 and 0.049, it shows a great diversity especially in the first stratum of 10 to 25 m. This study allows to evaluate species diversity in different fishing areas and consequences of the significant increase of fishing pressure on the stand and not only to focus on a few populations of species of commercial interest.

STRUKTUR UKURAN DAN TINGKAT PEMANFAATAN IKAN LENCAM (Lethrinus lentjan Lacepede, 1802) PERAIRAN ARAFURA DI PROBOLINGGO

2020 ◽  
Vol 13 (1) ◽  
pp. 128-138
Author(s):  
Andina Ramadhani Putri Pane ◽  
Nurulludin Nurulludin ◽  
Heri Widiyastuti ◽  
Ali Suman
Keyword(s):  
Size Structure ◽  
Stock Assessment ◽  
Demersal Fish ◽  
Fish Population ◽  
Fish Stock ◽  
Control Value ◽  
Scientific Analysis ◽  
Fish Exploitation ◽  
Fish Stock Assessment

AbstrakPenangkapan ikan di perairan Arafura banyak dilakukan oleh nelayan dari Pulau Jawa diantaranya Jakarta, Probolinggo, Pati, dan Indramayu. Nelayan dari Probolinggo yang menangkap ikan di perairan Arafura (WPP 718) menggunakan alat tangkap jaring dan pancing rawai dengan tujuan utama adalah ikan demersal, yaitu kakap (Lutjanus spp.), kerapu (Epeniphelus spp.), lencam (Lethrinus lentjan.), dan lainnya. Pemanfaatan ikan demersal terutama ikan lencam (Lethrinus lentjan) yang terus-menerus akan memicu terjadinya perubahan stok populasi ikan di perairan, sehingga diperlukan analisa ilmiah sebagai dasar pengelolaan perikanan. Tujuan dari analisa ilmiah ini untuk menjadi nilai kontrol dalam pengawasan jumlah eksploitasi ikan dan bahan pengkajian stok ikan lencam (Lethrinus lentjan). Penelitian dilakukan Februari hingga Desember 2017 di TPI Mayangan Probolinggo. Struktur ukuran ikan 23–65 cmFL dengan dominan pada ukuran 50 cmFL dengan ukuran pertama kali tertangkap (Lc) 44,5 cmFL. Laju pertumbuhan (K) 0,32 per tahun dengan panjang asimtotik 74 cmFL. Tingkat kematian karena penangkapan (F) lebih tinggi daripada tingkat kematian alami (M) dan tingkat eksploitasi E = 0,57%, yang berarti telah terjadi overfishing. Pengurangan eksploitasi sebesar 14%, dan penetapan ukuran layak tangkap serta ukuran legal diperdagangkan dapat menjadi upaya dalam dalam menjaga populasi ikan lencam.Abstract Fishing in Arafura waters is mostly done by fishermen from Java, including Jakarta, Probolinggo, Pati, and Indramayu. Fishermen from Probolinggo who catch fish in Arafura waters (FMA 718) use fishing nets and longline fishing with the main purpose being demersal fish, namely snapper (Lutjanus spp.), Groupers (Epeniphelus spp.), Lencam (Lethrinus lentjan) and others. Exploitation of demersal fish, especially lencam fish (Lethrinus lentjan) which will continually trigger changes in fish population stock in waters, so the scientific analysis is needed as a basis for fisheries management. The purpose of this scientific analysis is to become a control value in monitoring the amount of fish exploitation for fish stock assessment  (Lethrinus lentjan). The study was conducted from February to December 2017 at TPI Mayangan Probolinggo. The size structure of fish 23–65 cmFL with a dominant size of 50 cmFL with the length at first capture (Lc) 44.5 cmFL. Growth rate (K) 0.32 per year with an asymptotic length of 74 cmFL. The fishing mortality (F) is higher than the natural mortality (M) and the exploitation level E = 0.57%, which means overfishing has occurred. The 14% reduction in exploitation and the determination of catch size and legal size of trade can be an effort in maintaining fish populations.

Integrating Anisakis spp. parasites data and host genetic structure in the frame of a holistic approach for stock identification of selected Mediterranean Sea fish species

Parasitology ◽  
2014 ◽  
Vol 142 (1) ◽  
pp. 90-108 ◽  
Author(s):  
S. MATTIUCCI ◽  
R. CIMMARUTA ◽  
P. CIPRIANI ◽  
P. ABAUNZA ◽  
B. BELLISARIO ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Stock Assessment ◽  
Spatial Scales ◽  
Holistic Approach ◽  
Fish Population ◽  
Fish Host ◽  
Fish Stock ◽  
Stock Identification ◽  
Fish Stocks ◽  
Fish Stock Assessment

SUMMARYThe unique environment of the Mediterranean Sea makes fish stock assessment a major challenge. Stock identification of Mediterranean fisheries has been based mostly from data on biology, morphometrics, artificial tags, otolith shape and fish genetics, with less effort on the use of parasites as biomarkers. Here we use some case studies comparing Mediterranean vs Atlantic fish stocks in a multidisciplinary framework. The generalized Procrustes Rotation (PR) was used to assess the association between host genetics and larval Anisakis spp. datasets on demersal (hake) and pelagic (horse mackerel, swordfish) species. When discordant results emerged, they were due to the different features of the data. While fish population genetics can detect changes over an evolutionary timescale, providing indications on the cohesive action of gene flow, parasites are more suitable biomarkers when considering fish stocks over smaller temporal and spatial scales, hence giving information of fish movements over their lifespan. Future studies on the phylogeographic analysis of parasites suitable as biomarkers, and that of their fish host, performed on the same genes, will represent a further tool to be included in multidisciplinary studies on fish stock structure.

Fish stock assessment a manual of basic methods

Marine Policy ◽  
1984 ◽  
Vol 8 (1) ◽  
pp. 68-69
Author(s):  
Stephen J. Lockwood
Keyword(s):  
Stock Assessment ◽  
Fish Stock ◽  
Fish Stock Assessment

scholarly journals Accuracy of Acoustic Methods in Fish Stock Assessment Surveys

Sonar Systems ◽  
10.5772/18631 ◽  
2011 ◽  
Author(s):  
S. Georgakarakos ◽  
V. Trygonis ◽  
J. Haralabous
Keyword(s):  
Stock Assessment ◽  
Fish Stock ◽  
Acoustic Methods ◽  
Fish Stock Assessment

Fish Stock Assessment Working Group, CCAMLR, Hobart, 25 October–17 November 1989

1990 ◽  
Vol 2 (2) ◽  
pp. 180-181
Author(s):  
Karl-Hermann Kock
Keyword(s):  
Working Group ◽  
Stock Assessment ◽  
Fish Stock ◽  
Fish Stock Assessment ◽  
October 17

Catchability: a key parameter for fish stock assessment

1996 ◽  
Vol 6 (2) ◽  
Author(s):  
Francisco Arregu�n-S�nchez
Keyword(s):  
Stock Assessment ◽  
Fish Stock ◽  
Fish Stock Assessment ◽  
Key Parameter
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