Interaction between small pelagic purse seine fishery and its top predators

Abstract

Due to very good collaboration with one commercial purse seiner, using “Srdelara” and operating in fishing zone G, preliminary data concerning the interaction between small pelagic purse seine fishery and its predators were obtained. According to the notes taken by experience observer on-board in period from year 2013 to 2016, seems that tunas, dolphins and swordfish were the faithful companions of purse seiner fisherman with abundance of 68.6%, 22.0% and 9.4%, respectively. Although they were present all year round, their monthly pattern of appearance indicated that less tunas were recorded in May-June, more dolphins were noted from July to October while swordfish were mostly abundant in winter (January-March). Within the investigated period, slightly increasing trend of tuna and dolphins’ appearance was recorded, although statistically not significant. Analysing possible correlation between purse seine catches and predator’s abundances, revealed that appearance of tuna had negative impact on the catches (dispersion of schools), while realised catches in presence of dolphins were quite good so it seems that they tend to round up small pelagic fish schools.

Whales and dolphins of the Adriatic Sea

“…Off the eastern and southern coasts of the Adriatic, commercial purse seining is intensive (Lucchetti et al, 2018) but information on potential interactions with this fishery is scant, possibly because most purse seining happens at night. In the inshore waters off southern Croatia, Zorica et al (2018) conducted observations in 2013-2016 from a single purse seiner operating at night with fishing lights, and concluded that "dolphins" (most likely bottlenose dolphins) were present year-round, with a higher occurrence between July and October. On average, there were dolphins near the purse seiner 22% of the time.…”

“…On average, there were dolphins near the purse seiner 22% of the time. The authors contended that dolphins "help rounding up the school of small pelagic fish as no decrease in catches due to its appearance were noted, actually higher catches were realised in their presence" (Zorica et al, 2018). In Montenegro, bottlenose dolphin interactions with fishing boats including purse seiners were reported by Rudd et al (2022), but no other information is available.…”