In the Eastern North Pacific, tagging studies have been carried out by the California Department of Fish and Game (Anon. 2001), and more recently by the National Marine Fisheries Service, Southwest Fisheries Science Center (Holts and Kohin 2003, Holts et al. 2004). Using a consistent sample size of 28 sets of 200 hooks during each of eight years (1994–1997, 2000–2003), catch per unit effort (CPUE) data showed a slight decline (Holts et al. (2004); y = -0.0696x + 1.0982, R2 = 0.5107). However, it does not appear to be sufficient to warrant serious concern about the population. The large horizontal (primarily north-south along the coastline, but with some inshore-offshore movements) (Holts et al. 2004) and vertical (up to ~ 500 m) (Holts and Kohin 2003; Sepulveda et al. 2004) movements of Shortfin Makos, a behavior that could make them more or less available to the gear spatially but not necessarily indicating a population decline. Likewise, for males and females, there appeared to be a slight increase in the average size caught over the same eight years (y = 1.8368x + 112.38, R2 = 0.3751). This, combined with the CPUE changes would suggest that the biomass indices had not changed. The variability among years in CPUE can also be attributed to inter-annual oceanographic and climate changes, especially water temperature (http://www.pcouncil.org/hms/hmsback.html). Thus, although there are no precise or accurate population estimates, it appears that the population of shortfin makos in the eastern north Pacific has been relatively stable. (Taylor and Holts 2001, PFMC 2003).
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