Non-indigenous Japanese oyster drill Pteropurpura (Ocinebrellus) inornata (Récluz, 1851) (Gastropoda: Muricidae) on the south-west coast of Portugal

The Japanese oyster drill or rock snail Pteropurpura (Ocinebrellus) inornata (Récluz, 1851), a marine mollusc, belonging to the family Muricidae, is reported from Portugal for the first time. This non-indigenous species, most likely introduced accidentally from French oyster rearing areas into mainland Portugal, has been regularly sampled in shellfish-culture and nearby environments in Sagres, Algarve, Southwest Portugal since 2005–2008. Detailed studies are urgently needed in order to assess whether or not it has become an invasive species due to a range expansion beyond its point of initial introduction. Outputs should provide information to decision-makers to predict and limit further spread which might result in biodiversity loss and negative economical consequences in locally species-rich areas.

First record of Anachis aliceae (Mollusca: Gastropoda: Columbellidae) in the Algarve, south coast of Portugal

The marine gastropod Anachis aliceae (Pallary, 1900) is reported with certainty for the first time from the Algarve, south coast of Portugal from species-rich rocky priority biotope. Several live specimens of this species belonging to the Columbellidae family were collected and identified from by-catch samples, recovered from octopus traps set at depths between 50 and 70 m off Ponta da Piedade. Taxonomic validation of the newly recorded species is based on the comparison to other related species within the genus.

Bioaccumulation and effects of TBT on molluscs from southern Portugal

Tese de dout. Ciências e Tecnologias do Ambiente, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2004

An experimental study of gill net and trammel net 'ghost fishing' off the Algarve (southern Portugal)

Four 100 m lengths of both monofilament gill nets and trammel nets were deployed at depths between 15 and 18 m off the coast of the Algarve (south of Portugal) between April 1995 and June 1996. The nets were set on a natural rocky bottom with one end cut loose to simulate lost nets. Changes in net structure (net height, effective fishing area, movement, colonisation, wear and tear) and their catches (species, sizes, numbers, and biomass) were monitored by divers. Similar patterns were observed in all the nets, with a sharp decrease in net height and effective fishing area, and an increase in visibility within the first few weeks. Net movement was negligible except in the case of interference from other fishing gears. Catch rates were initially comparable to normally fished gill nets and trammel nets in this area, but decreased steadily over time. No sea birds, reptiles or mammals were caught in any of the 8 nets. Catches were dominated by fish (89 % by number, at least 27 species), in particular by sea breams (Sparidae) and wrasses (Labridae). Under the conditions experienced throughout the study the fishing Lifetime of a 'lost' net is between 15 and 20 wk. Based on an exponential model, we estimated that 100 m lengths of gill net and trammel net will catch 314 and 221 fish respectively over a 17 wk period. However, we consider this to be an underestimate due to high rates of predation and scavenging by octopuses, cuttlefish, moray eels, conger eels, and other fish such as the wrasse Coris julis. When the nets were surveyed in the following spring, 8 to 11 mo after being deployed, they were found to be completely destroyed or heavily colonised by algae and had become incorporated into the reef.

Bycatch of crustacean and fish bottom trawl fisheries from southern Portugal (Algarve)

As part of two research projects for analysing bycatch and discards, we quantified catch composition, catch rates, bycatch and discard,, in two important commercial bottom trawl fisheries (crustacean and fish trawls) off the Southern coast of Portugal (Algarve). Stratified sampling by onboard observers took place from February 1999 to March 2001 and data were collected from 165 tows during 52 fishing trips. Commercial tat-get species included crustaceans: blue and red shrimp (Aristeus antennatus), deep-water rose shrimp (Parapenaeus longirostris), Norway lobster (Nepharops norvegicus); and fishes: scabreams (Diplodus spl). and Pagellus Spp.), horse Mackerels (Trachurus spp.) and European hake (Merluccius merluccius). The trawl fisheries are characterised by considerable amounts of bycatch: 59.5% and 80.4% of the overall total catch for crustacean and fish trawlers respectively. A total of 255 species were identified, which belonged to 15 classes of organisms ( 137 vertebrates, 112 invertebrates and algae). Crustacean trawlers had higher bycatch biodiversity. Bony fish (45.6% and 37.8%) followed by crustaceans (14.6% and 11.5%) were the dominant bycatch components of both crustacean and fish trawlers respectively. The influence of a number of factors (e.g. depth, fishing gear, tow duration and season) on bycatch and discards is discussed.

Comparative Behavior of Wild and Hatchery Reared White Sea Bream (Diplodus sargus) Released on Artificial Reefs Off the Algarve (Southern Portugal)

Three hatchery produced and reared (HPR) and five wild white sea bream (Diplodus sargus) were double tagged with Vemco V8SC-2L acoustic transmitters and Floy Tag T-bar anchor tags, and released on artificial reefs located near a natural reef off the southern coast of Portugal. Passive telemetry was used to monitor movements of the white sea bream over a nine week period from April to June 2007. Differences in behavior at release, habitat association (artificial vs. natural reef), and in daily movements were registered. Wild fish moved from one habitat to the other with increased preference for the artificial habitat during the day, whereas HPR fish showed no site fidelity or consistent daily movement pattern and left the release site soon after release. Comparison of Minimum Convex Polygon (MCP) showed a higher area usage by wild fish. This experiment shows that these artificial reefs are used on a daily basis by wild white sea bream but apparently are not optimal release locations for hatchery produced white sea bream.

Weight-length relationships for fish species discarded in commercial fisheries of the Algarve (southern Portugal)

Weight and length descriptive statistics are reported for 73 fish species discarded in the commercial fisheries from the south coast of Portugal. Parameters of the weight-length relationship were estimated for 57 of these species. These are the first weight-length parameters reported for 20 of these species. For an additional 16 species for which no weight-length parameters have been reported, the parameter a was estimated by setting b = 3.0. Samples were used from five gear types: crustacean trawler, fish trawler, pelagic purse seine, demersal purse seine and trammel net. Samples were obtained from depths ranging from <30 m to >500 m and included pelagic and demersal species.

First record of Ocinebrina nicolai (Mollusca: Gastropoda: Muricidae: Ocenebrinae) in North-Eastern Atlantic waters

Ocinebrina nicolai Monterosato, 1884 a marine mollusc belonging to the Muricidae family is reported from Algarve, south coast of Portugal for the first time and is a new record for the biodiversity of the Portuguese malacological fauna and northeastern Atlantic waters. This species with a medium-size shell for the genus (14–16 mm) was initially sampled during a baseline project that studied marine biotopes in the central Algarve region. This short note presents a brief diagnosis of the species, provides local information on geographical distribution, habitat, and compares it with other congeneric species found in Portugal: Ocinebrina aciculata (Lamarck, 1822) and Ocinebrina edwardsii (Payraudeau, 1826).

The efficacy of releasing caught Nephrops as a management measure

The objective of this work was to examine if a policy of releasing caught lobsters, Nephrops, could be used to protect the Nephrops population off the south coast of Portugal. Such a measure, as an alternative to closing the fishery completely, would allow the continued operation of the fleet in targeting other species, resulting in a reduced economic and social impact compared with a complete closure. For such a proposal to be considered, information on survival rates of released lobsters is required. Nephrops were sampled randomly from the catch of commercial trawlers and put in cages, in an area with similar conditions to the area where they were caught, in order to evaluate survival rates. The cages were immersed for periods of 5–9 days. Several factors were considered to potentially affect survival, including duration of the tow and season, and biological characteristics of the individuals (e.g. size, sex and ovigerous condition). Survival was only affected by season (increased mortality inwarm months).Aglobal estimate of survival of released lobsters, taking into consideration survival and proportion of the catches for each season, was 35%. Simulation models were used to investigate the potential effect of a release measure on the population. Assuming the number of recaptured individuals is negligible, Z (instantaneous total mortality rate)would be considerably reduced if a release policy was implemented. This is particularly important if the levels of exploitation are high, which seems to be the case in this stock. It is our belief that the implementation of amanagement measure of returning all caught lobsters to the sea is worth considering as a means of aiding recovery of the resource. This measure would have the side effect of discouraging the choice of Nephrops as a target species, potentially reducing the fishing mortality even more significantly.

A comparison of monofilament gillnet and small hook longline selectivity in a multispecies artisanal fishery in the Algarve, Southern Portugal

As part of ongoing studies concerned with the small-scale fisheries of the South of Portugal, experimental fishing was carried out with monofilament gillnets and small hook longlines within the same area. Sixty-two species were caught, of which 20 were common to both gears. Pronounced differences in terms of the relative importance of different species in the catches were observed. Size selection patterns also differed, with highly overlapped hook catch distributions and few species showing evidence for size selectivity. In contrast, strong selectivity was characteristic of species which tend to be "wedged" in gillnets. Whereas smaller stretched mesh sizes (particularly 40 and 50 mm) caught significant numbers of illegal sized fish, this was minimal in the longlines. Some implications for management are discussed.