Hugo Diogo

Deep-water longline fishing has reduced impact on Vulnerable Marine Ecosystems

Bottom trawl fishing threatens deep-sea ecosystems, modifying the seafloor morphology and its physical properties, with dramatic consequences on benthic communities. Therefore, the future of deep-sea fishing relies on alternative techniques that maintain the health of deep-sea ecosystems and tolerate appropriate human uses of the marine environment. In this study, we demonstrate that deep-sea bottom longline fishing has little impact on vulnerable marine ecosystems, reducing bycatch of cold-water corals and limiting additional damage to benthic communities. We found that slow-growing vulnerable species are still common in areas subject to more than 20 years of longlining activity and estimate that one deep-sea bottom trawl will have a similar impact to 296–1,719 longlines, depending on the morphological complexity of the impacted species. Given the pronounced differences in the magnitude of disturbances coupled with its selectivity and low fuel consumption, we suggest that regulated deep-sea longlining can be an alternative to deep-sea bottom trawling.

Recreational boat fishing pressure on fish communities of the shelf and shelf break of Faial and Pico Islands (Azores Archipelago): implications for coastal resource management

Recreational fishing is one of the most popular leisure activities in coastal areas of the world, involving large numbers of participants and consequently responsible for high levels of fishing effort (Cowx 2002, McPhee et al. 2002, Pitcher and Hollingworth 2002). Scientific research on recreational fishing in recent decades has experienced worldwide growth bringing to light evidence of the negative impacts of this sector on marine coastal areas, which are similar to those known for commercial fisheries. The consequences of recreational fishing usually go far beyond direct impacts on the exploited species to those that occur on marine ecosystems (e.g., truncation of the natural age and size structure, trophic changes, loss of genetic variability and evolutionary changes) (McPhee et al. 2002, Coleman et al. 2004, Cooke and Cowx 2004, Cooke et al. 2006). Despite this known fact, few countries have based their fisheries management policies on both recreational and commercial fishing data. Fishery managers are just beginning to fully understand the importance of integrating information for both sectors. In part, this change of perspective was related with the increasing awareness of the global overfishing process (Cooke and Cowx 2004). A transition from subsistence fishing to recreational fishing has been seen in many areas of the world (e.g., Mediterranean Sea) and was due in large part to economic development and led to several structural changes in the ACTA ICHTHYOLOGICA ET PISCATORIA (2013) 43 (4): 267–276 DOI: 10.3750/AIP2013.43.4.02

Using information-based methods to model age and growth of the silver scabbardfish, Lepidopus caudatus, from the mid-Atlantic Ocean

Abstract The traditional species targeted by the Azorean demersal mixed hook-and-line commercial fisheries are presently facing a decline in captures, and the demand for new demersal resources is growing. The silver scabbardfish, Lepidopus caudatus, is a potential new resource to be exploited in the region; however, reports on its vulnerability and stock status are contradictory, which highlights the importance of arriving at accurate age and growth parameter estimates for this species. The 808 individuals used in the present study were acquired from commercial landings in the Azorean islands of São Miguel and Faial, collected monthly between 2004 and 2010. Ages were determined by counting growth increments in whole sagittal otoliths. Four different growth models were fitted to the data: von Bertalanffy growth function, the Gompertz model, the logistic model and the power function. Akaikes Information Criterion was used to evaluate the models and finally a multi-model inference was employed to arrive at model-averaged estimates of L∞. The von Bertalanffy function performed as well as the other candidates, although the parameter estimates for this model were usually higher than for the Gompertz and logistic models. The analysis suggests that L. caudatus is a relatively fast-growing species that could constitute a sustainable resource for commercial fisheries in the region, pending further research into the unbalanced sex ratios observed here.