Table 3. — Concentrations of Pleuroncodes planipes, adults and juveniles (not larvae), in ml./lO 'm.' of water strained, on 



cruise 6608 



' After station 47, on northbound track between lat. 26°30' N. and 27°50' N., at night. 



temperature data (Scripps Institution of Ocean- 

 ography, 1961), but no data on chlorophyll or red 

 crabs. Cruise coverage and property distributions 

 are shown in figures 9 and 10. Data on red crabs 

 are given in table 4. 



Surface temperatures were between 18° and 

 30° C. but the areas under 20° C. and over 28° C. 

 were extremely restricted (fig. 10). The cold 

 inshore region between Point San Eugenio and 

 San Pablo Point probably represents upwelling 

 at a very late stage. A large tongue or tongues 

 of relatively cool water (less than 25° C.) ran 

 offshore from the coastal upwelling area as shown 

 for previous cruises. No such signs of relatively 

 cool water were off Magdalena Bay, where ui:)well- 

 ing probably ceases earlier than it does farther 

 north. 



Observations on surface chlorophyll a were 

 fewer on this cruise than on the others. Concentra- 

 tions were much lower than before — from 0.11 to 

 0.02 mg./m.^, which is consistent with the indica- 

 tions of a further weakening of upwelling. Con- 

 centrations were at or above 0.1 mg./m.^ only at 

 stations 20, 30, 37, 38, 41, and 42. The isogram of 

 0.05 mg./m.^ follows the 25° C. isotherm fairly 

 well (fig. 10), so the oflFshore tongue of relatively 

 cool water generally had a higher concentration 

 of chlorophyll than the surrounding warmer 

 water. 



The area in which concentrations of red crabs 

 exceeded 40 ml./l,000 m.^ was broadly congruent 

 with the area of cool water and the area of highest 

 surface chlorophyll. The isograms of these three 

 properties tend to be displaced a little from each 



other, but otherwise they agree in considerable 

 detail. There was an isolated patch of red-crab- 

 rich water off Magdalena Bay; it was not cool, 

 and chlorophyll was not sampled in this particular 

 area. 



About half of the tuna catches that were made 

 at the time of the cruise were north of Abreojos 

 Point, where data on chlorophyll and red crabs 

 are lacking; temperatures were mostly over 20° C. 

 Tlie catches to the south of Abreojos Point all were 

 from water over 20° C. and show the kind of asso- 

 ciation with chlorophyll and red crabs that was 

 mentioned for cruise 6608. The tuna were not only 

 on the edges of the biologically rich areas but in 

 the cores of these areas as well. The areas of 

 abundant forage, which on cruise TO-64-2 were 

 too cold for tunas except at the edges, were warm 

 enough for the fish to penetrate on this cruise. As 

 before, tuna distribution was not determined 

 (insignificant amount of fishing) in certain large 

 areas, including some in which temperature and 

 food conditions appeared highly suitable. 



CRUISE TO-65-1 



This cruise (figs. 11 and 12), which was in Sep- 

 tember 1965, represents a still later stage in the 

 year, when the distribution of surface temperature 

 gives no indication of any coastal upwelling. The 

 lowest temperatures, between 20° and 21° C, were 

 offshore and probably indicate California Current 

 water. The highest temperatures were slightly 

 over 28° C. Temperatures on part 2 of the cruise 

 were about the same as on part 1. On CalCOFI 

 cruise 6509, which extended into the northern part 

 of the area near the end of cruise TO-65-1, sur- 



164 



U.S. FISH AND WILDLIFE SERVICE 



