Abstract.— Tlie annual migratory 

 cycle of Argentine hake Meriuccius 

 hubhsi was related to environmental 

 conditions in the Southwestern At- 

 lantic Ocean. In late summer-early 

 fall, hake move northward and off- 

 shore towards feeding grounds. A 

 southward and inshore migration 

 towards spawning grounds occurs in 

 early spring. The ends of the migra- 

 tory circuit are associated with pro- 

 ductive ocean fronts. Differences in 

 the migratory pattern between 1978 

 and 1979 were tied to fluctuations in 

 the latitude of the confluence of the 

 Brazil and Malvinas currents along 

 the shelf break. 



Migratory Pattern of Argentine 

 Hake Meriuccius hubbsi and 

 Oceanic Processes in tiie 

 Soutlnwestern Atlantic Ocean 



Guillermo P. Podesta 



Rosenstiel School of Marine and Atmospheric Science, University of Miami 

 4600 Rickenbacker Causeway, Miami, Florida 33149 



Manuscript accepted 20 September 1989. 

 Fishery Bulletin, U.S. 88:167-177. 



Tlie Argentine hake Meriuccius hubb- 

 si is the most important species in 

 Argentine fisheries: its landings 

 make up approximately two thirds (in 

 weight) of all Argentine fish catches. 

 Fishery surveys carried out at differ- 

 ent times of the year, together with 

 data on the movements of the com- 

 mercial fishing fleet, have revealed 

 seasonal changes in hake distribu- 

 tion. The inshore spawning migi'ation 

 of adult hake on the Argentine shelf 

 was first described by Hart (1946). 

 Using data from a commercial trawl- 

 er, Angelescu et al. (1958) showed 

 the change in depth distribution of 

 hake throughout the year. Christian- 

 sen and Cousseau (1971) and Bellisio 

 et al. (1978) described the seasonal 

 movements of the Argentine fishing 

 fleet targeting on hake. An extensive 

 research program sponsored by 

 UNDP-FAO between 1968 and 1975 

 resulted in an improved knowledge of 

 the distribution and migration of Ar- 

 gentine hake (FAO 1975). Otero and 

 Kawai (1981) proposed the existence 

 of two Argentine hake stocks, one 

 migrating approximately between 

 35 °S and 44 °S and another moving 

 between 44°S and 50°S. Chung and 

 Tanaka (1985) investigated the dis- 

 placements of hake using a 1-year 

 series of research cruises. Otero 

 (1986) used several years of commer- 

 cial fishery data to describe the 

 migration of hake, showing the pro- 

 gressive expansion of effort towards 

 the southern part of the Argentine 

 shelf. 



Despite our knowledge of the sea- 

 sonal distribution of hake, not much 

 is understood about the oceanic con- 

 ditions which contribute to define the 

 migi-atory pattern of the species. The 

 objective of this paper, therefore, is 

 to explore the association between 

 the migi-ation of hake and environ- 

 mental conditions in the southwest- 

 ern Atlantic Ocean off Argentina and 

 Uruguay. A usual approach is to 

 treat fish distribution as a function of 

 one or a few environmental variables 

 (e.g., water temperature, salinity). 

 Instead, emphasis is placed here on 

 physical features, such as ocean 

 fronts of diverse nature, which are an 

 intrinsic part of the Argentine shelf 

 ecosystem. I will discuss the rele- 

 vance of these features to the differ- 

 ent migratory stages (and, therefore, 

 varying biological requirements) of 

 hake. Historical fishery and hydro- 

 graphic data are used to establish 

 links between the distribution of hake 

 and oceanic features; any such links 

 may form the basis of specific 

 hypotheses that can be rigorously in- 

 vestigated in the future. 



Data and methods 



The primary data used to determine 

 the migratory pattern of hake include 

 catch, effort (trawling hours), and 

 area of operations (by 1 -degree 

 squares) reported by the Argentine 

 offshore fishing fleet in 1978 and 

 1979. A detailed description of the 

 fishery data is presented by Podesta 



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