
%0 Journal Article
%A Holts, DB 
%A Bedford, DW 
%T Horizontal and vertical movements of the shortfin mako shark, <I>Isurus oxyrinchus</I>, in the Southern California Bight
%J Marine and Freshwater Research
%D 1993/12/01
%V 44
%N 6
%P 901-909
%K tagging, tracking, water temperature
%R https://doi.org/10.1071/MF9930901
%U https://www.publish.csiro.au/paper/MF9930901 
%X Recreational and commercial fishing effort directed at the shortfin mako shark, Isurus oxyrinchus,  off the coast of southern California increased markedly in the mid 1980s. However, very little is  known about the population size, stock structure or movements of these sharks in the northern  Pacific. It is important to determine their role in these waters because the southern California bight  may be an important pupping and nursery area for shortfin mako sharks. Acoustic telemetry was  used to identify short-term horizontal and vertical movements of three shortfin mako sharks in the  southern California bight during the summer of 1989. All three sharks were two-year-old juveniles  and were tracked for periods of from 18 to 25 h. They spent 90% of their time in the mixed layer,  with only infrequent excursions below the thermocline. Vertical and horizontal movements did not  indicate any diel activity pattern associated with distance to the shore or nearby islands or with  bottom topography. 
