MICROSATELLITE MARKERS REVEAL SIGNIFICANT POPULATION GENETIC STRUCTURE OF THE LEBRANCHE MULLET (MUGIL LIZA) IN SOUTH AMERICA COASTAL WATERS

ANA CECILIA MAI; CAROLINA ISABEL MIÑO; LUIS F. F. MARINS; JORGE P CASTELLO; VALÉRIA LEMOS; CASSIANO MONTEIRO-NETO; LAURA MIRANDA; PAULO R SCHWINGEL; MARIANO GONZÁLEZ-CASTRO; DANIEL P LOEBMANN; JOAO P VIEIRA

Maringá, PR

Congreso; XX Encontro Brasileiro de Ictiologia; 2013

Mugil liza is a Mugiidae distributed in the Western Atlantic from Argentina (AR) toVenezuela with a high commercial and social value in the small-scale and thepurse-seine fisheries in Brazil. Between April to May, large shoals start thereproductive migration leaving estuaries and coastal lagoons from AR andUruguay, joining large migrating shoals of Rio Grande do Sul (RS), Santa Catarina(SC), and other southern Brazilian states. During migration, mullets are especiallyvulnerable to fishery, and more than 90% of total dense shoals catches are madein SC and RS. Identifying the origin of the catches is urgent for a responsible andeffective fishery management. We investigated the genetic structure of mulletpopulations using nine heterologous polymorphic microsatellites. A total of 250adults were sampled from Rio de Janeiro (RJ), São Paulo (SP), SC, RS and AR.Fst indicated significant genetic differentiation between RJ and all the otherlocations (all P-values ≤ 0.01). Samples from SP and AR showed low geneticdistances. Bayesian cluster analyses indicated that two was the number ofpopulations that best explained the observed distribution of genetic diversity.Based on these results, we suggest that there are at least two different geneticdemes: one including mullets from AR to SP, subjected to a strong fishingpressure; another including fishes from RJ (and probably northern locations).Given that fishing may be affecting two different genetic clusters, there is urgentneed for a fisheries management plan that takes into account genetic data.Moreover, as little information is available on range distribution and fisheries?pressures for RJ mullets, further studies should be carried out to establish thenorthern limit of this population and to elucidate the existence of other geneticpopulations