Mario Sbrana

Fishery of the deep-water rose shrimp Parapenaeus longirostris (Lucas, 1846) (Crustacea: Decapoda) in the northern Tyrrhenian Sea (western Mediterranean)

The aim of this study is to provide information on the fishing pattern of Parapenaeus longirostris in the northern Tyrrhenian Sea (western Mediterranean), in order to improve the management of the resource in the area. Data were obtained from commercial fishery, covering the period 1991–2002. Catch rates revealed notable inter-annual fluctuation of the P. longirostris landing, probably due to the life cycle of the species. The highest yields (kg per hour of trawl) of the commercial fishery were obtained at depths ranging between 180 and 300 m, the lower ones at depths between 100 and 180 m, where small specimens are more abundant. Commercial catches were characterised by a very low presence of specimens smaller than 20 mm carapace length (CL), mainly due to the deeper localisation of the fishing grounds when compared to the recruitment areas of the species. The size at which 50% of the specimens were discarded by the fishermen was 15 mm CL, while the estimated size at first capture of the individuals caught by the commercial net was 12.4 mm CL.

Once upon a Time in the Mediterranean Long Term Trends of Mediterranean Fisheries Resources based on Fishers' Traditional Ecological Knowledge

We investigate long-term changes in the Mediterranean marine resources driving the trawl fisheries by analysing fishers’ perceptions (Traditional Ecological Knowledge, TEK) throughout the Mediterranean Sea during the last 80 years. To this end, we conducted an extended set of interviews with experienced fishers that enabled us to classify species (or taxa) as ‘decreasing’ or ‘increasing’ both in terms of abundance, as well as average size in the catch. The aspect that most clearly emerged in all the investigated areas over time was the notable increase of fishing capacity indicators, such as engine power and fishing depth range. Atlantic mackerel, poor cod, scorpionfishes, striped seabream, and John Dory demonstrated a decreasing trend in the fishers’ perceived abundance, while Mediterranean parrotfish, common pandora, cuttlefish, blue and red shrimp, and mullets gave indications of an increasing temporal trend. Although, as a rule, trawler captains did not report any cataclysmic changes (e.g. extinctions), when they were invited to estimate total catches, a clear decreasing pattern emerged; this being a notable finding taking into account the steep escalation of fishing efficiency during the past century. The overall deteriorating status of stocks in most Mediterranean regions calls for responsible management and design of rebuilding plans. This should include historical information accounting for past exploitation patterns that could help defining a baseline of fish abundance prior to heavy industrial fisheries exploitation.

Effects of environmental and anthropogenic drivers on the spatial distribution of deep-sea shrimps in the Ligurian and Tyrrhenian Seas (NW Mediterranean)

In the Mediterranean Sea, Aristaeomorpha foliacea and Aristeus antennatus are the most important target species of deep-sea trawl fisheries. Previous studies performed in several areas of the Mediterranean highlighted the key role played by both environmental factors, such as temperature, and anthropogenic activities, such as fishing, in affecting the abundance and distribution of the two species. The present study is aimed at investigating the effects of environmental and anthropogenic drivers on the abundance and spatial distribution of A. foliacea and A. antennatus in the Ligurian and northern and central Tyrrhenian Seas (NW Mediterranean). To this end, the time series of MEDITS trawl survey data (1994–2015) were analyzed together with environmental variables, namely sea surface temperature, current speed, and fishing effort by means of GAM. The results show that fishing plays an important role in shaping the spatial distribution of the two species. A. antennatus is prevalent where fishing effort is higher; this can be related to the higher resilience of blue and red shrimp to fishery impact. In contrast, high temperatures are associated to the prevalence of A. foliacea. Therefore, the abundance and spatial distribution of this species is mainly driven by temperature.