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We explore the capability, willingness and practicalities of data collection by skippers, and the feasibility of using these data to document fishing patterns and catch composition in the English inshore sector. Thirty skippers of under 10 m vessels in south coast England collected detailed information on the gear they used, species, size, proportion of catch retained and discarded as well as the reasons for discarding during daily fishing trips. Fisheries observers accompanied participating vessels on prearranged trips to independently record the catch levels and collect length data. The data from skippers showed significant differences between gear types on the level of daily catch with the daily catch for gill net, otter trawl and tangle net significantly higher than that of drift net, hand line and ring net. Discard rates varied between the different gear types with trammel net (27%) and tangle net (22%) showing the highest discards ratios, while hand lines (4%) the lowest. Comparison of the number of species recorded by skipper and observer on the same fishing trips shows that the number recorded by observer was two times that of the skipper indicating that skippers are poor at identifying species in the discarded catch as they do not pay a lot of attention to this portion of the catch. Catch data from corresponding trips also show low correlations between the self-collected data from skippers and data from observers. Accurate discard rates are important as they are applied to landings data to estimate total catch and therefore total fishing mortality. Results show that the skippers consistently underestimated the discard rates when compared to the observer data implying that weighting factors will be needed if the data from skippers are to be used in stock assessments. [ABSTRACT FROM AUTHOR]

Accuracy of angler-reported data on steelhead, Oncorhynchus mykiss (Walbaum), harvest in Idaho, USA, was quantified by comparing data recorded on angler harvest permits to the numbers that the same group of anglers reported in an off-site survey. Anglers could respond to the off-site survey using mail or Internet; if they did not respond using these methods, they were called on the telephone. A majority of anglers responded through the mail, and the probability of responding by Internet decreased with increasing age of the respondent. The actual number of steelhead harvested did not appear to influence the response type. Anglers in the autumn 2012 survey overreported harvest by 24%, whereas anglers in the spring 2013 survey under-reported steelhead harvest by 16%. The direction of reporting bias may have been a function of actual harvest, where anglers harvested on average 2.6 times more fish during the spring fishery than the autumn. Reporting bias that is a function of actual harvest can have substantial management and conservation implications because the fishery will be perceived to be performing better at lower harvest rates and worse when harvest rates are higher. Thus, these findings warrant consideration when designing surveys and evaluating management actions. [ABSTRACT FROM AUTHOR]

Abstract: Abundance indices are difficult to derive from multispecies catch-per-unit-effort (CPUE) data as these critically rely on the ability to account for targeting behaviour that directs effort towards a particular target species or species-complex. We developed a novel standardization method that uses continuous principal component scores, derived from a Principal Component Analysis of the catch composition data, as non-linear predictor variables for targeted effort within a Generalized Additive Model (GAM) framework. This ‘Direct Principal Component’ method (DPC) is compared to a commonly used standardization approach, in which clusters of fishing tactics are identified from the catch composition and treated as categorical variables. We employed GAMs, which incorporate spatial, seasonal, and fishing power effects, to evaluate the statistical performance of the two alternative sets of covariates. The GAMs were applied to CPUE datasets from the South African hand-line fishery, covering three fishing regions over a period of 26 years, to provide abundance indices for two commercially important species, carpenter, Argyrozona argyrozona and silver kob, Argyrosomus inodorus. Results show that both approaches removed substantial variation from the CPUE data, but that the DPC approach was statistically superior as judged by the AIC, deviance explained and results from 10-fold bootstrap cross-validations. The DPC method represents a more direct approach, is less time-consuming and subjective and therefore considerably easier to implement. We present evidence that the DPC was able to account for substantial shifts in targeting without masking the year effect. The standardized CPUE time series showed positive responses for both species as total landings decreased due to forced effort reductions in 2000. The approach presented here has potentially unlocked useful information for stock assessment in the over two million individual catch records available for the South African hand-line fishery and similar multispecies fisheries. [Copyright &y& Elsevier]

Abstract: Rapid growth of popular and lucrative catch-and-release marine sportfisheries worldwide has highlighted the need for reliable weight estimation methods for use in fishing tournaments, pursuit of fishing records, and to support scientific research that allows captured fish to be released alive. This paper describes new methods to predict weight from measurements of body size of game fish. Here we also evaluated efficacy of a widely used historical model and compared this to several new statistical and analytical weight estimation models that we developed herein. We applied these candidate models to a unique morphometric data set on Atlantic tarpon (Megalops atlanticus) which contained information on body weight W as a function of fork length L and dorsal girth G for more than 1100 individuals from Florida, the Gulf of Mexico, Caribbean Sea and western Africa. A popular formula (W = G 2L/800), developed more than a century ago specifically for tarpon was originally derived from geometric and physical relationships between fish body weight and shape. We found this model to be negatively biased >−15% (i.e., underestimates individual fish weights) across the tarpon''s entire size range up to 130kg (the current world record). Bias for our “new” ellipsoid volumetric formulation, which extends the principles of allometry, was less than 1% across the entire range of observed sizes. Our new estimator was used by Texas Parks and Wildlife Department to assist fishery management in setting “minimum maximum” sizes for recreationally caught tarpon that have the potential to break the Texas State record. It has also supported catch-and-release tarpon fisheries and tournaments in Florida, Texas, Mexico, and Trinidad. It provides a reliable means to accurately estimate weights of tarpon of potential (world) record sizes. [Copyright &y& Elsevier]

Abstract: Enhancing selection using two-stage selection is normally implemented by pre-selection for tagging weight (BWT) and by final selection for ungutted harvest weight (BWH) and thermal growth coefficient from tagging to harvest (TGCTH). However, selection on harvest traits, i.e., gutted weight (GBWH), visceral percentage (VISW%), condition factor (CFH), and overall survival (SURV), can be enhanced by exploiting correlated traits. It can be hypothesized that the efficiency of two-stage selection on genetic response in BWH and TGCTH is dependent on their genetic (r g) and phenotypic (r p) correlations with BWT and therefore dependent on the time point of pre-selection. The aims of this study were, first, to estimate genetic parameters (heritability: h 2, r p, and r g) for BWT (7months), BWS (weight at sorting, 9months), BWH (14months), TGCTH, GBWH, VISW%, CFH, and SURV. Second, these genetic parameters were used in two deterministic simulation studies; i) one- and two-stage selections to compare genetic responses in BWH and TGCTH, and ii) alternative selection indices using correlated traits to compare corresponding accuracy of selection (r IH) for slaughter traits, CFH, and SURV. Genetic parameters were estimated using an animal mixed model in ASReml on 2,041 fish records. The main results showed that, first, r g of BWT was 0.35 with BWH but −0.25 with TGCTH, whereas the r g of BWS was 0.72 with BWH but 0.39 with TGCTH. Pre-selection for BWS led to genetic response of 54.15g in BWH which was higher than the genetic response from pre-selection for BWT (51.90g). Similarly, pre-selection on BWS enhanced correlated genetic response in TGCTH to 0.30g(1/3)/°C*day. In contrast, pre-selection for BWT resulted in lower correlated genetic response in TGCTH of 0.20g(1/3)/°C*day. It can be concluded that genetic improvement of BWH and TGCTH can be enhanced by postponing pre-selection to a later age. However, an optimal time point for tagging and pre-selection should be found to minimize common environmental effects and rearing costs during communal rearing of full-sibs. Second, including GBWH in a selection index can reduce unfavourable selection responses in VISW%. The GBWH is highly genetically correlated with BWH and can be easily indirectly selected. TGCTH is a good predictor for selection for lower VISW%, and higher SURV, but not for higher CFH. To control genetic changes in the condition factor, it should be included to the selection index. [Copyright &y& Elsevier]

Abstract: Self-reporting of information is an inexpensive means for collecting data on fishing or other human activities, but the accuracy of self-reported data can be difficult to measure. Logbooks that record fishing activities are a common form of self-reporting that can provide vast amounts of information about a fishery. Using logbook data from trawlers from Oregon ports operating along the US Pacific coast during 1987–2001, this study examined (a) the consistency of reported tow locations and bottom depths and (b) the accuracy of reported retained catches of four groundfish species groups. Because logbook data during this period played no direct role in fishery management or stock assessments, there were no obvious incentives for trawl captains to deliberately report false logbook information. To evaluate consistency between tow locations and corresponding bottom depths, each tow was assigned to a 100-m bottom depth-band based on the reported tow location on a digital chart. The depth-bands based on the tow locations were then compared one-to-one with the depths reported in the logbooks and analysed to determine factors (e.g., year, quarter, vessel) contributing to the consistency between the reported locations and depths. Consistency was highest in the shallowest depth-bands and there was a strong interaction between depth and vessel. To evaluate the accuracy of the retained catches reported by the captains, the tow-by-tow logbook data were summed to the fishing-trip-level and compared to the official landing weights, recorded at the fish processing plants when the catches were off-loaded and weighed. The logbook weights relative to the corresponding official landing weights were analysed using zero-inflated generalized Poisson (ZIGP) regression models to determine factors (year, quarter, vessel) that were important explanatory variables. The analysis found strong year, quarter, and vessel effects for all three parts of the ZIGP: the mean value, the dispersion, and the proportion of zeros. The vessel effect was strongest. In a combined analysis, based on results from the other two analyses, vessels that were consistent in recording their depths and fishing locations had only a weak tendency to be accurate in recording their catches. [Copyright &y& Elsevier]

The article discusses an August 2014 report in the journal "Marine Policy" regarding researchers' urging of the International Game Fish Association (IGFA) in Dania Beach, Florida to stop record-keeping, arguing that it encourages the killing of endangered fish, which the IGFA disputes.