Yield and catch changes in a Mediterranean small tuna trap: a warming change effect?

Abstract

Since the 17th century, the Tonnarella of Camogli, a small tuna trap, has been used to catch pelagic fish along the western coast of the Portofino Promontory (Ligurian Sea, Northwestern Mediterranean). The availability of long-term datasets on fish yields (1950-1974 and 1996-2011), with information related to the seawater temperatures and the North Atlantic Oscillation (NAO), has allowed us to study the qualitative and quantitative changes in fish yields in the last decade and the possible relationships with the seasonal anomalies of temperature that have occurred in the Ligurian Sea. In 1950-1974, yields remained relatively constant over time (average of 35.6 AE 8.7 tÁyear À1 ). From 1996 through 2011, yields were high (42.9 AE 15.9 tÁyear À1 ) but inconsistent with strong annual variability in catches. The primary catches are Seriola dumerili, Auxis rochei, Trachurus spp. and Sarda sarda. Changes in species composition have occurred as well: S. dumerili, Sardinella sp. and Belone belone have appeared recently. Moreover, a significant decrease in the boreal scombroid (Scomber scombrus) and an increase of warm-temperate carangids and other typically Southern Mediterranean species such as Coryphaena hippurus and Sphyraena viridensis, appear to be linked to the warming of the surface water layer, particularly evident in the Ligurian Sea, for the last 10 years. The analysis of this kind of trend may be a powerful tool for assessing structural changes of the pelagic fish community in the Ligurian Sea (Northwestern Mediterranean).

Long‐term comparison of structure and dynamics of the red coral metapopulation of the Portofino Promontory (Ligurian Sea): a case‐study for a Marine Protected Area in the Mediterranean Sea

“…; Cattaneo‐Vietti et al . ). In particular, a series of trans‐phyletic mass mortalities events also greatly affected the red coral in the entire Ligurian‐Provencal basin (Cerrano et al .…”

Over 10 years of variation in Mediterranean reef benthic communities

“…Global warming has been shown to be among the main factors triggering mass mortality events (Bavestrello et al., ; Cattaneo‐Vietti et al., ; Cerrano & Bavestrello, ; Cerrano et al., ; Garrabou et al., ; Schiaparelli et al., ). In the Portofino area, between 2002 and 2013, the surface seawater temperature experienced an increase of a 0.1°C as an annual average, with summer peaks exceeding by 2–3°C the monthly average, compared to the previous decade (Cattaneo‐Vietti et al., ). The benthic communities, down to 40 m depth, were greatly affected by warming events in 1999, 2003 and 2006.…”

“…Several taxa have been studied during recent decades in this area: i.e., macroalgae (Mangialajo et al., ), Posidonia oceanica meadows (e.g., Montefalcone et al., ), sponges (Pansini & Musso, ; Pansini & Pronzato, ; Pronzato, Bavestrello, & Cerrano, ), hydrozoans (Boero, Balduzzi, Bavestrello, Caffa, & Cattaneo‐Vietti, ; Puce et al., ), red coral and other octocorals (Bavestrello, Bo, Bertolino, Betti, & Cattaneo‐Vietti, ), and fish (Cattaneo‐Vietti, Cappanera, Castellano, & Povero, ; Tunesi & Molinari, ).…”

Assessing interacting impacts of artisanal and recreational fisheries in a small Marine Protected Area (Portofino, NW Mediterranean Sea)

“…Other traditional fishing gears (e.g., tonnarella targeting small pelagic, and mugginara , specifically targeting mugilids) are allowed during specific periods and are restricted to a single site within zone C of the MPA (Cattaneo‐Vietti et al. ). Recreational fishing is permitted for residents of the three municipalities under authorization in zones B and C and for non‐residents only in zone C. For both recreational and artisanal fishing, other restrictions such as the fishing of some species, spatial closures, prohibitions or modifications of fishing techniques, regulations in fishing effort, and minimum landing sizes are also implemented in the MPA to control the activities, according to the MPA Regulation (2008) (Markantonatou et al.…”