Seasonal variations in gross biochemical composition, percent edibility, and condition index of the clam Ruditapes Decussatus cultivated in the Ria Formosa (South Portugal)

The grooved carpet shell clam, Ruditapes decussatus (L. 1758), is one of the most popular and profitable molluscs exploited in rearing plots in the Mediterranean. However, annual catch has been declining steadily since the early nineties. In order to understand the seasonality of its nutritional value, thus providing an improved basis for economical valuation of the resource, gross biochemical composition, percentage edibility and condition index were investigated during a year with monthly periodicity in a commercially exploited population of the clam Ruditapes decussatus in the Ria Formosa, a temperate mesotidal coastal lagoon located in the south of Portugal. Our results show that total and non-protein nitrogen co-varied during the year, resulting in a protein content that peaked in the warmest months. Although complementary in summer, carbohydrate and lipid contents showed irregular annual trends. The observed seasonality was comparable to that shown by studies elsewhere at similar latitudes, and are underpinned by the reproductive cycle of the species. Our results show the clams to be at their prime nutritional value at the beginning of summer, when protein content peaks.

Assessment of reserve effect in a marine protected area: the case study of the Professor Luiz Saldanha Marine Park (Portugal)

Dissertação de mest., Biologia Marinha (Ecologia e Conservação Marinhas), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

The impact of the Arrábida Marine Park (Portugal) on the decapod crustacean Eualus cranchii: a case study

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Univerisdade do Algarve, 2015

Evaluation of the economic impact of tourism expenditures in Portugal

Dissertação de Mestrado, Economia do Turismo e Desenvolvimento Regional, Faculdade de Economia, Universidade do Algarve, 2015

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

Recruitment patterns and processes of coastal fish species in a temperate rocky reef

Tese de Doutoramento, Ciências do Mar, da Terra e do Ambiente, Ramo: Ciências do Mar, Especialização em Ecologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016

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).

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.