No mullet, no gain: cooperation between dolphins and cast net fishermen in southern Brazil

By

Lang Dos Santos, Mauricio
Lemos, Valéria Marques
Vieira, João Paes

Type

Article

Date of Publication

2018-10-19

Original Publication

MycoKeys

Volume

35

Pages

1--13

Subjects

Fishing activity , Generalized Linear Models , liza , Mugil , seasonality , Tramandaí River Estuary , truncatus , Tursiops

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers 2011-

Identifiers

DOI: https://doi.org/10.3897/zoologia.35.e24446

 

Abstract

We report on the interaction between common bottlenose dolphins, Tursiopstruncatus (Montagu, 1821) and cast net fishermen in southern coast of Brazil. The fishery was monitored in the mouth of the Tramandaí River Estuary to investigate the seasonality of catches and their relationships with a set of variables: presence/absence and number of bottlenose dolphins, fishing area, temperature, salinity, wind and water flow direction in the channel. The mullet, Mugilliza Valenciennes, 1836 is the target species and was the dominant fish in the catches (77% of total catch; 50% in frequency; 0.2 ind. x f-1). The use of GLM models helped to reveal that the number of the bottlenose dolphins, time of year (months) and spatial variation of fishing activity were the main factors explaining the presence and abundance of mullet in the fishermen’s catches. The presences of bottlenose dolphins in the fishing area raise the probability of fishermen catch larger number of mullets with smaller fishing effort. However, the size of the mullet is influenced basically by seasonality. The mullets are the “currency” of bottlenose dolphins and fishermen interaction. There are reasons for concern about the sustainability of the southern Brazilian M.liza stock, once the decrease of this fishing resource can lead this rare and traditional fishery to the extinction.