Citizen science data suggest that a novel rig improves landing rate and reduces injury and handling time in recreational angling with artificial lures in Baltic pike (Esox lucius).

The optimal terminal gear in hook-and-line recreational fishing maximizes landing rates and minimizes injury to the fish because some fish will be released after capture. We designed a novel rig configuration in artificial lure fishing for top predators and examined its effectiveness in angling for Baltic northern pike (Esox lucius) using a citizen science approach based on observational data collected from volunteer anglers in the field. The novel rig included two changes to traditional rig designs common to artificial lure angling. First, hooks were mounted in a way giving better hook exposure and eliminating lever-arm effects from the lure to the hooks once a fish is hooked. This construction allowed the second change, being a shift to hooks 4-5 sizes smaller than those used on traditional hook mounts. We analysed observational data collected by volunteer anglers using either the novel rig or a standard rig mount in two types of artificial lures (softbait and hardbait) of the same size (about 17 cm). Using N = 768 pike contacts as input data, we showed the landing rates of pike targeted with artificial lures significantly and substantially increased from 45% with normal-rigs to 85% when the same lure types were fished with the novel rig configuration. Lure type and water temperature had no effects on landing rates. Moreover, hardbaits on normal-rigs produced significantly more injury, bleeding and elevated unhooking time compared to fish captured on hardbaits with release-rigs. We conclude that simple changes to traditional hook sizes and mounts in lure fishing may benefit both anglers and the fishes that are to be released and that citizen science projects with volunteer anglers are able to provide good data in proof-of-concept studies. Further experimental studies are needed to differentiate hook size from hook mount effects because both variables were confounded in the results of the observational data presented here.

Evaluation of geostatistical estimators and their applicability to characterise the spatial patterns of recreational fishing catch rates.

Western Australians are heavily engaged in recreational fishing activities with a participation rate of approximately 30%. An accurate estimation of the spatial distribution of recreational catch per unit effort (catch rates) is an integral component for monitoring fish population changes and to develop strategies for ecosystem-based marine management. Geostatistical techniques such as kriging can provide useful tools for characterising the spatial distributions of recreational catch rates. However, most recreational fishery data are highly skewed, zero-inflated and when expressed as ratios are impacted by the small number problem which can influence the estimates obtained from the traditional kriging. The applicability of ordinary, indicator and Poisson kriging to recreational catch rate data was evaluated for three aquatic species with different behaviours and distribution patterns. The prediction performance of each estimator was assessed based on cross-validation. For all three species, the accuracy plot of the indicator kriging (IK) showed a better agreement between expected and empirical proportions of catch rate data falling within probability intervals of increasing size, as measured by the goodness statistic. Also, indicator kriging was found to be better in predicting the latent catch rate for the three species compared to ordinary and Poisson kriging. For each species, the spatial maps from the three estimators displayed similar patterns but Poisson kriging produced smoother spatial distributions. We show that the IK estimator may be preferable for the spatial modelling of catch rate data exhibiting these characteristics, and has the best prediction performance regardless of the life history and distribution patterns of those three species.

Efecto de factores ambientales y la asignación del esfuerzo pesquero sobre las capturas de la raya Aetobatus narinari (Rajiformes: Myliobatidae) en el sur del Golfo de México / Effect of environmental factors and fishing effort allocation on catch of the Spotted Eagle Ray Aetobatus narinari (Rajiformes: Myliobatidae) in Southern Gulf of Mexico

Aetobatus narinari represents a fisheries target in Southern Gulf of Mexico, and it is currently considered a Near Threatened species by the IUCN red list. The information available of this batoid fish includes some biological and fishery aspects; nevertheless, little is known about the factors influencing on fishing operations and catches. In order to evaluate the effect of environmental factors and the fishing effort allocation by vessels on the target fishery of A. narinari in this area, a daily basis sampling was carried out on four small-scale vessels, from January to July 2009 (the entire fishing season), in two fishing localities (Campeche and Seybaplaya). A total of 896 rays were recorded from 280 fishing trips. A General Linear Model was used to predict the factors effect on the probability that fishing operations occurred, and on the probability for captures of at least one or three or five rays per vessel-trip. The probability that fishing operations occurred off Campeche was predicted by the lunar cycle, with the highest probability in the new moon period (66%) and a probability smaller than 35% for the other periods. The probability that fishing operations occurred off Seybaplaya was predicted by wind velocity, with higher probabilities at low wind velocity than at high wind velocity, and a 50% probability of fishing operations at 12-15km/h. Catch rates off Seybaplaya were predicted by the vessel´s factor (the effect of fishing effort allocation), the North wind season and sea surface temperature. The probability for captures of at least one and three rays per vessel-trip was predicted by the vessel´s factor and the North wind season. One vessel had higher catch probability (83% for at least one ray and 43% for at least three rays) than the others (69 and 70% for at least one ray and 26% for at least three rays), and during the North wind season the catch probability was higher (96% for at least one ray and 72% for at least three rays) than out of that season (68% for at least one ray and 21% for at least three rays). The probability for capture at least five rays per vessel-trip was predicted by the sea surface temperature and the North wind season. At 23°C the catch probability was of 49% and the probability gradually diminished to 4% at 28°C, and during the North wind season the catch probability was higher (40%) than out of that season (7%). This study shows that some environmental factors and fishermen perceptions and experience (fishing effort allocation) influence on the catch rate of A. narinari, and that these factors must be considered in future studies on elasmobranch fisheries, mainly when comparisons between catch rates among seasons or regions are analyzed.

Aunque existen estudios sobre las pesquerías de batoideos en aguas Mexicanas, falta información sobre la influencia de factores sobre las operaciones pesqueras y las tasas de captura. Para evaluar el efecto de algunos factores en la pesquería dirigida sobre la raya pinta Aetobatus narinari en el Sur del Golfo de México, se realizaron registros diarios de las operaciones pesqueras de cuatro embarcaciones menores en dos localidades (Campeche y Seybaplaya), de enero a julio 2009 (temporada de pesca completa). Fueron registradas 896 rayas en 280 viajes de pesca. Se utilizó el Modelo General Lineal para evaluar la influencia de los factores en las operaciones de pesca y las tasas de captura. La operación pesquera fue predicha por el ciclo lunar (frente a Campeche) y la velocidad del viento (frente a Seybaplaya). Las tasas de captura frente a Seybaplaya fueron predichas por el factor embarcación, la temporada de frentes fríos y la temperatura superficial del mar. Este estudio demuestra que tanto los factores ambientales como las diferencias en la asignación del esfuerzo pesquero entre embarcaciones, influyen en las tasas de captura, por lo que deben ser considerados en estudios futuros que comparen tasas de captura entre estaciones del año y regiones.

Influencia del ciclo lunar en la captura de langosta espinosa Panulirus argus (Decapoda: Palinuridae) en el Golfo de Batabanó, Cuba

Influence of lunar cycle on catches of spiny lobster Panulirus argus (Decapoda: Palinuridae) in the Gulf of Batabanó, Cuba. Many biological processes such as reproductive and migratory behaviours have been associated with moon cycles. In this study, the nocturnal light levels associated with lunar cycle (INT) were correlated with daily catch rate of lobster P. argus, during seven lunar months of 2002 fishing period, to determine a possible relationship between these variables. The lobster catches were obtained from three fishing companies that develop their activities in the Gulf of Batabanó: EPICOL that fishes in Coloma area; PESCAHABANA in Batabanó area and PESCAISLA in Isla area. Daily catch per boat (CDB) was used as a measurement of daily catch variations (catch rate). The correlation was analyzed showing it in chronological graphs based on average of CDB per lunar phases, comparing lobster catch rate per lunar phases -with the Kruskal-Wallis test-. Spearman rank correlation coefficient and cross correlation techniques were also applied. Similarities between lobster catch rate and the lunar cycle were not found. Spearman rank correlation coefficient was modularly smaller than 0.1 in all cases and demonstrated quantitatively that correlation between CDB and INT does not exist. Kruskal-Wallis test detected differences only in Batabanó area but not when making the analyses for the whole Gulf of Batabanó. Finally, the cross correlations do not detected significance in any zone, as well. It is concluded that, in opposition to what other authors have reported, the catch rates of P. argus and the lunar cycle did not show significant correlation in the Gulf of Batabanó. This trend was independent of the fishing art, which varied according to the time of the year that was analyzed. Rev. Biol. Trop. 59 (1): 207-216. Epub 2011 March 01.

Muchos procesos biológicos tales como los comportamientos reproductivos y migratorios se han asociado con los ciclos de la luna. Con el objetivo de determinar la relación entre las capturas de langosta espinosa Panulirus argus (Decapoda: Palinuridae) y el ciclo lunar, en la zona del Golfo de Batabanó, se correlacionaron los niveles de iluminación nocturna del ciclo lunar (INT) con la captura diaria por barco (CDB) durante siete meses lunares correspondientes al período de pesca del 2002. Los datos de captura provinieron de las tres empresas pesqueras que realizan su actividad en la zona del Golfo de Batabanó. La relación entre el ciclo lunar y las capturas de langostas fue examinada mediante varios procedimientos estadísticos. Los primeros gráficos realizados, cualitativos, mostraron que no existe relación entre las tasas de captura y el ciclo lunar. Los coeficientes de Spearman calculados, modularmente menores que 0.1 en todos los casos, demostraron cuantitativamente que no existe correlación entre las mencionadas variables. La prueba de Kruskal-Wallis detectó diferencias sólo en una de las tres áreas estudiadas. Las correlaciones cruzadas no detectaron significación en ninguna de las zonas, con coeficientes de correlación cruzada modularmente inferiores a 0.1. A diferencia de lo reportado por otros autores, las capturas de P. argus y el ciclo lunar no presentan correlación significativa en el Golfo de Batabanó.