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- Testing Nordmore grids on the target and by-catch species of the commercial bottom trawl fishery in the Gulf of CadizPublication . Gamaza, MariÁngeles; Sobrino, Ignacio; Erzini, KarimSorting grids have been tested worldwide in trawl fisheries. Here we report upon the first trials performed using Nordmore sorting grids with four different bar spacings in the trawl fisheries of the Gulf of Cadiz targeting crustaceans as the main resource. A total of 288 valid hauls and 67 commercial species were caught. Escapement and escape size selectivity were evaluated for the most important target and by-catch species. A decrease in the percentage of biomass escape was recorded with increasing grid spacing for the two target species, deep-water rose shrimp (Parapenaeus longirostris) and Norway lobster (Nephrops norvegicus), from 24% to 8% for the former and from 86 to 9% for the latter, with a 15-mm and 30-mm grid respectively. In general, high escape rates were found for most finfish and cephalopods. For hake (Merluccius merluccius), as the main by-catch species, the results showed an escape rate decreasing from 96% to 71% as the bar spacing increased. Our findings suggest the 30-mm grid would be effective for the deep-water crustacean trawlers but different mitigation measures will be required for other metiers in the multispecies trawl fishery of the Gulf of Cadiz.
- Reproductive aspects of the undulate ray, Raja undulata, from the south coast of PortugalPublication . Coelho, Rui; Erzini, KarimThe maturity of the undulate ray, Raja undulata, one of the most important by-catch elasmobranch species captured in south Portugal, was studied for the first time. Females ranged in total length (TL) from 19.4 to 88.2 cm and males from 23.0 to 83.2 cm. The gonadosomatic index for females was higher during the winter, meaning that this species reproduces during this season. Females matured at significantly larger sizes and older ages than males, with 50% of the females mature at 76.2 cm TL at an age of 8.98 years while 50% maturity for males was achieved at 73.6 cm TL and 7.66 years. Females were mature at 86.3% of the maximum observed size and 69.1% of the maximum observed age while males matured at 88.5% of the maximum observed size and 63.8% of the maximum observed age, making this a very late maturing species, with important consequences in terms of fisheries management and conservation. (c) 2006 Elsevier B.V. All rights reserved.
- Catches in ghost-fishing octopus and fish traps in the northeastern Atlantic Ocean (Algarve, Portugal)Publication . Erzini, Karim; Bentes, L.; Coelho, Rui; Lino, P. G.; Monteiro, P.; Ribeiro, J.; Gonçalves, J. M. S.Ghost fishing is the term used to describe the continued capture of fish and other living organisms after a fisherman has lost all control over the gear. Traps may be lost for a variety of reasons including theft, vandalism, abandonment, interactions with other gear, fouling on the bottom (i.e., traps and ropes are caught on rocky substrate), bad weather, and human error (Laist, 1995). Annual trap loss can be as high as 20% to 50% of fished traps in some fisheries (Al-Masroori et al., 2004). Because lost traps can continue to fish for long periods, albeit with decreasing efficiency over time (e.g., Smolowitz, 1978; Breen, 1987, 1990; Guillory, 1993), ghost fishing is a concern in fisheries worldwide.
- Age and growth of megrim, Lepidorhombus boscii, Risso of the portuguese continental coastPublication . Castilho, Rita; Dinis, Maria Teresa; Erzini, KarimThe first study of age and growth of four-spotted scaldfish, more commonly known as megrim (Lepidorhombus boscii, Risso), an important (by catch ) species of the Portuguese trawl fishery from the Atlantic coast is presented. The analysis was based on data obtained from a total of 609 specimens sampled between 1985 and 1986. Otoliths were used for age determination. The Von Bertalanf~, growth parameters were estimated using the non-linear fitting method: Lt (females)=440[ 1 -e -°-14(t+ 1.32) ] and Lt= 375 [ 1 -e -°~4(t+ 1.93) ] for males. L~ and to values are significantly different. The megrim grows allometrically (slope of length-weight regressions > 3 ). Females live longer and gain weight at a faster rate than males. Differences in growth between sexes become more apparent from the second year onwards.
- Soft-bottom fishes and spatial protection: findings from a temperate marine protected areaPublication . Sousa, Inês; Gonçalves, Jorge Manuel Santos; Claudet, Joachim; Coelho, Rui; Gonçalves, Emanuel J.; Erzini, KarimNumerous studies over the last decades have focused on marine protected areas (MPAs) and their effects on fish communities. However, there is a knowledge gap regarding how species that live associated with soft-substrates (e.g., sand, mud) respond to spatial protection. We analyzed abundance, biomass and total lengths of the soft-bottom fishes in a multiple-use MPA in the north-eastern Atlantic, the Luiz Saldanha Marine Park (Portugal), during and after the implementation of its management plan. Data were collected by experimental fishing in areas with three different levels of protection, during the implementation period and for three years after full implementation of the MPA. Univariate analysis detected significant biomass increases between the two periods. Fish assemblages were mainly structured by depth and substrate, followed by protection level. Community composition analyses revealed significant differences between protection levels and between the two periods. Species exhibited a broad variation in their response to protection, and we hypothesize that factors such as species habitat preferences, body size and late maturity might be underlying determinants. Overall, this study provides some evidence of protection effectiveness in soft-bottom fish communities, supported by the significant increase in biomass in the protected areas and the positive trends of some species.
- Movements of Sarpa salpa (Linnaeus, 1758) (Sparidae) in a coastal lagoon (Ria Formosa, Portugal)Publication . Abecasis, D.; Bentes, L.; Erzini, KarimThe salema, Sarpa salpa (Linnaeus, 1758), is a sparid with a distribution that includes the eastern Atlantic coast from the Bay of Biscay to South Africa, as well as the Azores, Madeira, Canary and Cape Verde archipelagos. It is also found in groups in the Mediterranean Sea and the Indian Ocean from South Africa to Mozambique, living on sandy and seagrass bottoms ranging from 0 to 70 m depth (Bauchot and Hureau, 1986). The species is a protandrous hermaphrodite where, according to Criscoli et al. (2006), sex change occurs between 24 and 31 cm total length (3–7 years old). While the economic value of S. salpa in fisheries is relatively limited, its ecological importance is well recognized, with several studies on its biology and interactions on seagrass meadows (e.g. Verlaque, 1990; Criscoli et al., 2006). As an herbivore Sarpa salpa has a strong impact with seagrass meadows, being responsible for much of the herbivory (Verlaque, 1990; Cebria´n et al., 1996; Prado et al., 2008), and representing a considerable part of the ichthyofauna in these habitats (Francour, 1997, 2000). Studies on S. salpa diel activity patterns, home range and habitat utilization in the Mediterranean Sea were undertaken by Jadot et al. (2002, 2006). These studies have revealed two behaviours, with some fish being highly sedentary while others use larger areas; great variation in mobility was found, with some fish showing both behaviours. The core areas (95%) range between 1600 and 279 000m2 , with some fish presenting diel movement patterns between day and night areas as well as homing abilities. The Ria Formosa, in the southern part of Portugal, is a shallow coastal lagoon with large meadows of seagrasses (Zostera noltii, Zostera marina and Cymodocea nodosa) where the influence of S. salpa on these communities is still unknown. Previous studies on the ichthyofauna of the Ria Formosa coastal lagoon focused largely on temporal and spatial changes in species composition (Monteiro et al., 1990; Ribeiro et al., 2006, 2008). Up to the present, the acoustic telemetry studies carried out in the Ria Formosa focused on the movements and home range of Sparus aurata (Abecasis and Erzini, 2008) and Diplodus spp. (Abecasis et al., 2009). A preceding tag-recapture study of juveniles of S. salpa (between 8.2 and 16.7 cm total length) provided limited information, with only a few recaptures (Abecasis, 2007). The present study was carried out to determine the movement patterns of S. salpa inside a coastal lagoon (Ria Formosa, south Portugal) in order to provide basic information on their home range and site fidelity.
- The EU landing obligation and European small-scale fisheries: What are the odds for success?Publication . Veiga, Pedro; Pita, C.; Rangel, Mafalda; Gonçalves, J. M. S.; Campos, Aida; Fernandes, P. G.; Sala, Antonello; Virgili, M.; Lucchetti, A.; Brcic, J.; Villasante, S.; Ballesteros, Marta A.; Chapela, R.; Santiago, Jose Luis; Agnarsson, S.; Ögmundarson, O.; Erzini, KarimA landing obligation was formally implemented in the European Union (EU) for the first time, as part of the recent reform of the EU Common Fisheries Policy (CFP). Given the reasonable success of the landing obligation in some countries such as the Faroe Islands, Iceland and Norway, this policy is seen as a viable approach to tackle the long-recognized discarding problem in EU waters. However, there has been some debate on whether there is sufficient evidence to support the feasibility of such a measure in the EU-CFP. The EU landing obligation will implicitly include all small-scale fisheries (SSF) provided the species captured are subject to catch limits or minimum sizes (in the case of the Mediterranean). SSF were included irrespective of the fact that the discarding problem in the EU has been historically associated with medium- to large-scale fleets (in particular largely mixed species trawl fisheries). Additionally, past experiences with a discard ban policy are still limited to specific countries and/or specific fisheries. This paper examined the appropriateness and feasibility of the recently implemented EU landing obligation in SSF. The effects in the long-term are unpredictable, but available evidence suggests that in the short to medium-term a landing obligation is likely to bring more negative social, economic and ecological impacts than benefits. (C) 2015 Elsevier Ltd. All rights reserved.
- Seagrass feeding choices and digestive strategies of the herbivorous fish Sarpa salpaPublication . Goldenberg, Silvan U.; Erzini, KarimThis is the first study investigating the plant-herbivore interaction between Sarpa salpa, which has overgrazed seagrass transplants in Portugal, and the seagrasses Cymodocea nodosa, Zostera marina and Zostera noltii, which have been considered for restoration. When offered the choice between the three seagrasses in outdoor tanks, adult S. salpa clearly preferred Z. noltii. Testing the seagrasses separately, mean +/- s.d. feeding rates ranged from 21 +/- 11g seagrass fresh mass kg(-1) fish mass day(-1) for Z. marina to 32 +/- 9g seagrass fresh mass kg(-1) fish mass day(-1) for C. nodosa and 40 +/- 11g seagrass fresh mass kg(-1) fish mass day(-1) for Z. noltii (temperature=16 degrees C). Food-processing rate in S. salpa did not differ between seagrasses, and there was no evidence of a regulation of processing rate according to food intake. Seagrasses differed substantially in nitrogen content and C:N, with C. nodosa containing the highest nitrogen content and lowest C:N (2.5 +/- 0.1% and 14.0 +/- 1.0), followed by Z. noltii (2.1 +/- 0.1% and 17.0 +/- 1.0) and Z. marina (1.4 +/- 0.1% and 26.0 +/- 2.0). Food-processing rate in S. salpa and the nutritional value of the seagrasses were not correlated with the observed feeding preference and rate. The study suggests that C. nodosa and Z. marina are less at risk of overgrazing by S. salpa and might thus be preferable to Z. noltii for seagrass restoration in areas with noticeable abundances of this fish.
- Feeding habits of the deep-snouted pipefish Syngnathus typhle in a temperate coastal lagoonPublication . Oliveira, F.; Erzini, Karim; Gonçalves, J. M. S.Feeding habits of Syngnathus typhle were determined based on monthly sampling during experimental fishing in a coastal lagoon (Ria Formosa, South Portugal) from April 2004 to May 2002. The gut contents of 856 individuals were analysed and quantified with numerical and gravimetric methods, as well as with some complementary indices and measures (vacuity, fullness and relative importance). In this study, this species fed mainly on Copepoda, Mysidacea, small caridean grass shrimps (Hippolytidae and Palaemonidae) and small fishes (Gobiidae) and to a lesser degree on other small invertebrates. No significant differences were found between the diets of males and females. However, significant differences in the fullness indexes of both sexes were observed during the reproductive period. Significant differences in the diet among seasons were also verified but no seasonal trends were discovered. Snout length showed a linear increase with growth while mouth area and total length displayed an allometric relation. Mouth shape varied between an ellipse and an almost perfect circle. The increase in mouth area and snout length as S. typhle grows contributed to the observed ontogenic diet shift with specimens smaller than 10 cm feeding almost exclusively on Copepoda, medium sized specimens feeding mainly on Hippolytidae and Mysidacea, while larger specimens preyed on Hippolytidae, Palaemonidae and Gobiidae. Prey size generally increased with size of S. typhle. (c) 2007 Elsevier Ltd. All rights reserved.
- Interactions between air-breathing marine megafauna and artisanal fisheries in Southern Iberian Atlantic waters: results from an interview survey to fishersPublication . Alexandre, Sofia; Marçalo, Ana; Marques, Tiago A.; Pires, Alexandra; Rangel, Mafalda; Ressurreição, Adriana; Monteiro, Pedro; Erzini, Karim; Gonçalves, Jorge Manuel SantosThe coastal waters off Western Iberia are an important fishing ground and a marine megafauna foraging area. Overlap between fishery target species and the diet of several air breathing marine megafauna species can lead to negative interactions and consequently conservation and economic issues. This work aimed to assess marine megafauna (cetaceans, marine birds, and marine turtles) – fishery interactions through face-to-face interviews to fishers of the local and coastal artisanal fisheries fleets in the landing sites of the Portuguese mainland Southern coast (Algarve). The main goal was to identify and evaluate problematic interactions known to cause bycatch or economic loss through depredation. We found that bycatch is a concern for all marine megafauna groups, but depredation problems are mostly associated with cetaceans. Of the sampled artisanal fisheries (longlines, pots and traps, bottom set-nets, and purse seine), the fishing gears of most concern were purse seine and coastal bottom set-nets. Purse seine showed problems associated with important bycatch numbers, especially of common dolphins, Delphinus delphis, while bottom set-nets have considerable bycatch of all animal groups and depredation was highly associated with bottlenose dolphins, Tursiops truncatus. Bycatch and depredation were found to be species, gear, area, and vessel size dependent. Economic loss caused by depredation led to catch and gear damage and was widely reported by bottom set-net fishers, ranging from 7% to 21% of their revenue. Higher losses were reported for local vessels in leeward (eastern) Algarve area. This study showed that the active participation of fishers provides improved localized knowledge on interactions between local and coastal fisheries and marine megafauna, allowing for the definition of specific management and mitigation strategies.