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Fishery Bulletin 90(4). 1992 



unknown reason, recruitment in the even years tended 

 to be larger than it was in the odd years (Mann- Whitney 

 test, P = 0.06). 



Prior to 1978, it is difficult to estimate annual recruit- 

 ment because the data required to calculate FI were 

 not routinely collected. However, an examination of the 

 large increase in abundance in 1972 (Fig. 2A) cannot 

 be avoided. Interpretation of the 1972 increase is 

 troublesome because the evidence for an unusually 

 large recruitment is equivocal. A large recruitment, for 

 example, should have resulted in a large increase in the 

 proportion of the population comprised of fat ar- 

 morhead as it did in 1980 and 1986 (Fig. 4A,B), yet 

 the proportion of the population categorized as fat dur- 

 ing the period of maximum recruitment was smaller 

 in 1972 than it was in 1973 when recruitment did not 

 appear to be exceptionally large (Boehlert and Sasaki 

 1988). Armorhead measured in 1972, however, were 

 markedly smaller than in any other year (Takahashi 

 and Sasaki 1977, Borets 1975). One proposed explana- 

 tion for the small size is that the tremendous abundance 

 of armorhead in 1972 resulted in a density-dependent 

 suppression of growth in the pelagic phase (Borets 

 1977). This might also have reduced the FI of recruits 



in 



Ul 



< 



o 



CO 



0.0 0.2 0.4 0.6 0.8 1.0 



JAPANESE CPUE (MT/HR) 



Figure 9 



Biomass of pelagic armorhead Pseudopentaceros wheeleri on 

 Southeast Hancock Seamount and Japanese trawl catch/hr 

 on all other southern Emperor-northern Hawaiian Ridge 

 seamounts during (•) Period 1 (1985-90) and (O) Period 

 2 (1978-84) when the Southeast Hancock Seamount popula- 

 tion experienced fishing. 



and thereby masked the FI signature of a large 

 recruitment. 



An alternate explanation for the 1972 increase in 

 abundance is that it is an illusion due to a rapid increase 

 in trawl catchability as the newly-developed fishery 

 progressed from an exploratory phase to a production 

 phase (Takahashi and Sasaki 1977, Uchida and Tagami 

 1984). If, however, the 1972 increase was due simply 



