A simple statistical method for catch comparison studies

Holst, René; Revill, A.S.

doi:10.1016/j.fishres.2008.09.027

Cited by 106 publications

(103 citation statements)

References 7 publications

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“…Paired t-tests were performed to judge whether the differences in catch amount for two codends were statistically significant. GLMM (Generalised Linear Mixed Models) was used to compare the length of obtained the veined rapa whelk and three by-catch species (Holst and Revill 2009). The proportion of the veined rapa whelk and three by-catch species retained at total length by 72 mm square-mesh codend (SMC) was calculated for each length as: P = SMC count at length ÷ (SMC and CD total count at length).…”

Section: Methodsmentioning

confidence: 99%

“…The proportion of the veined rapa whelk and three by-catch species retained at total length by 72 mm square-mesh codend (SMC) was calculated for each length as: P = SMC count at length ÷ (SMC and CD total count at length). The polynomial regression GLMM (with random intercepts) was used to fit curves for the expected proportions of the total catch retained by the 72 mm square-mesh codend (Holst and Revill 2009). The glmmPQL function in MASS package of the R statistical software, which uses a penalized quasi-likelihood approach, was used to fit the GLMM model (Holst and Revill 2009).…”

Section: Methodsmentioning

confidence: 99%

“…The polynomial regression GLMM (with random intercepts) was used to fit curves for the expected proportions of the total catch retained by the 72 mm square-mesh codend (Holst and Revill 2009). The glmmPQL function in MASS package of the R statistical software, which uses a penalized quasi-likelihood approach, was used to fit the GLMM model (Holst and Revill 2009). The analyses proceeded by fitting the third order polynomials followed by subsequent reductions until all terms showed statistical significance (P < 0.05) based on the Wald's test, with the removal of one term at a time to determine the best-fit model as described by Holst and Revill (2009).…”

Section: Methodsmentioning

confidence: 99%

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Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Eryaşar¹

2018

Acta Ichthyol. Piscat.

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Eryaşar A.R. 2018. Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa. Acta Ichthyol. Piscat. 48 (2): 173-181.Background. The beam trawl fisheries of veined rapa whelk, Rapana venosa (Valenciennes, 1846), cause small benthic organisms to be captured and also damage the other species living on the seafloor. To solve this problem, a proper modification that minimise the by-catch should be designed and put into practice. This study aims to compare 72 mm commercial diamond-mesh codend with 72 mm square-mesh codend to reduce the benthic bycatch in this fishery. Materials and methods. Totally 15 hauls were carried out in south-eastern Black Sea Region within 10-14 August 2017. A commercial diamond-mesh and square-mesh beam trawls were towed simultaneously behind a commercial fishing vessel to compare the by-catch compositions. Paired t-test was used to compare the catch amount of two codends based on species. GLMM (Generalised Linear Mixed Models) was used to compare the length of captured veined rapa whelk, mussel, and crab species.Results. There was a 77-percentage-point reduction in the mean number of the captured individuals as by-catch in square-mesh codend when compared with commercial diamond-mesh codend and this difference was found statistically significant (P < 0.05). A total of 17 species was captured as by-catch in both codends. Comparing to diamond-mesh codend, the catch amount of the 13 by-catch species had decreased in square-mesh codend.Conclusions. In conclusion, the square-mesh codend was found successful in decreasing the by-catch amount of many benthic species except for flatfish species and large crabs. In addition to this, the veined rapa whelk amount fell by half and this means a 25-percentage-point profit decrease for fishermen.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Eryaşar¹

2018

Acta Ichthyol. Piscat.

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“…The proportion of catch at each length class for shrimp and major bycatch species from the control and experimental trawls was analyzed using the generalized linear mixed models (GLMM) with carapace length (shrimp) or fish length (bycatch) as the explanatory variable (fixed effect), the catch proportion as the response variable, the individual tow as the random effect, and subsample ratio as an offset, following the technique described in Holst and Revill (2009). The GLMM was implemented using the glmmPQL function in the MASS package (Venables and Ripley 2002) of R statistical software (R Core Team 2014), which used a penalized quasilikelihood approach (Breslow and Clayton 1993).…”

Section: Catch Sampling and Analysismentioning

confidence: 99%

Comparative fishing to evaluate the viability of an aligned footgear designed to reduce seabed contact in northern shrimp bottom trawl fisheries

Winger

Munden

Nguyen

et al. 2018

Can. J. Fish. Aquat. Sci.

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Abstract:We developed and evaluated an innovative trawl technology that reduces seabed contact while targeting northern shrimp (Pandalus borealis) off the east coast of Canada. The innovative footgear, referred to as the "aligned footgear", was evaluated in a flume tank to estimate contact area with the seabed and then tested at sea for engineering performance and catchability. Results demonstrated that the aligned footgear trawl produced a substantial reduction (i.e., 61%) in the predicted contact area with the seabed compared with the identical trawl equipped with traditional rockhopper footgear. A total of 20 paired tows (n = 40 tows) were subsequently conducted at sea to evaluate fishing performance. The aligned footgear trawl caught significantly more northern shrimp (+23%), capelin (Mallotus villosus) (+71%), and Greenland halibut (Reinhardtius hippoglossoides) (+99%) compared with the traditional rockhopper bottom trawl.Résumé : Nous avons mis au point et évalué une technique novatrice de pêche au chalut qui réduit le contact avec le fond marin en ciblant la crevette nordique (Pandalus borealis) au large de la côte est du Canada. Le bourrelet novateur, appelé « bourrelet aligné », a été évalué dans un bassin à circulation d'eau afin d'estimer l'aire de contact avec le fond marin, puis a fait l'objet d'essais en mer pour évaluer la performance technique et la capturabilité. Les résultats démontrent que le chalut à bourrelet aligné entraîne une réduction importante (c.-à -d. 61 %) de l'aire de contact prévue avec le fond marin par rapport au même chalut équipé d'un bourrelet sauteur classique. Un total de 20 traits appariés (n = 40 traits) ont ensuite été effectués en mer afin d'évaluer la performance de pêche. Le chalut à bourrelet aligné a pris des quantités significativement plus grandes de crevettes nordiques (+23 %), capelans (Mallotus villosus) (+71 %) et flétans noirs (Reinhardtius hippoglossoides) (+99 %) que le chalut de fond à bourrelet sauteur classique. [Traduit par la Rédaction]

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“…The approach suggested by Holst and Revill (2009) was adopted for the current dataset where polynomial generalised linear mixed model (GLMM) analyses were performed using the R software package. The GLMM method uses low-order polynomial approximations (3rd-order, logit link, net type fixed term) to fit the proportions at length retained in the square codend relative to the total numbers retained by both square and diamond codends, and produces realistic curves and variance estimate bands.…”

Section: Statistical Analysesmentioning

confidence: 99%

Performance of square-mesh codends in reducing discards and by-catch in the Shark Bay scallop fishery

Chandrapavan

Kangas

Sporer

2012

Mar. Freshwater Res.

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Abstract. The performance of square-mesh codends (as opposed to the conventional diamond mesh) was examined as a discard and by-catch reduction device for the Shark Bay saucer-scallop trawl fishery. Of the three different-sized squaremesh codends (50, 55, 60 mm) tested against the standard 100-mm diamond-mesh codend, the 50-mm square-mesh codend performed poorly with relatively high retention of small (,85 mm shell height) scallops, whereas the 55-and 60-mm square-mesh codends retained 22-33% less smaller scallops than did the diamond-mesh codend. Overall, a mean of 5% loss in commercial-sized scallops across all three square-mesh codends and significant by-catch reductions of up to 95% were achieved compared with the diamond mesh. Catch rate of prawns by the square-mesh codend was less than 2% of that of the standard prawn net. The performance of the 60-mm square-mesh codend presents a good basis for its use in commercial trials in the Shark Bay scallop trawl fishery. A move to square-mesh codends could result in a significant reduction of small scallops and by-catch and may potentially increase the catches of commercial-sized scallops as a result in improvements in water flow and net efficiency.

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A simple statistical method for catch comparison studies

Cited by 106 publications

References 7 publications

Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Comparative fishing to evaluate the viability of an aligned footgear designed to reduce seabed contact in northern shrimp bottom trawl fisheries

Performance of square-mesh codends in reducing discards and by-catch in the Shark Bay scallop fishery

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