FISHERY BULLETIN: VOL. 86, NO 1 



Table 6. — Between-year percent similarity index (PS!) values from compari- 

 sons of (A) total larvae and (B) \he OL (ottier larval taxa) fraction collected 

 during July-September sampling periods off northern Cfiile (18-24 S), 1964- 

 83. 



accommodations for possible sampling depth- 

 catch differences of Trachurus gayi and Triphotu- 

 rus mexicanus. 



When the PL are excluded, comparisons be- 

 tween the OL taxa yield generally lower PSI val- 

 ues than those of the total larvae; only 2¥7( of the 

 18.5-88.1 values are moderate to high (Table 6B). 

 Moderate to high values (69.9-88.1) come from 

 comparisons between 1964, 1965, 1967, and 1969, 

 and in part result from similar proportions of 

 Lampanyctus parvicauda (32.1-41.4%) and Tri- 

 photurus mexicanus (18.2—28.99^) during those 

 years. Moderate values (66.2-74.4) also come 

 from comparisons of 1967 vs. 1968 and 1969 (sim- 

 ilar proportions of L. parvicauda, T. mexicanus, 

 and Diogenichthys [12.2-39.5%!); 1970 vs. 1972 

 (similar proportions of Vinciguerria lucetia and 

 Diogenichthys [23.4-26.8%!); and 1972 vs. 1973 

 (similar proportions of Bathylagus nigrigenys, V. 

 lucetia, and Diogenichthys [9.3-25.3%!). Lowest 

 PSI values (<30) result from comparisons of 1966 

 vs. 1965, 1970, 1972, and 1983, and are due 

 largely to extreme dominance by Normanichthys 

 crockeri (67.4% of OL) in 1966. Recalculations to 

 accommodate for possible depth-related increased 

 catches of T. mexicanus in most cases decrease 

 1973 and 1983 PSI values (e.g., by 2.6-7.2) and in 

 two cases (1968 and 1970 vs. 1973) change the 

 value characterization from moderate (67.9 and 

 68.4) to low (63.8 and 64.5). With one exception 



(1972 vs. 1973, PSI = 67.0) 

 justed values are low. 



all of the other ad- 



Species Across-Year Ranked 

 Abundance Patterns 



Individual species across-year abundance rank- 

 ings demonstrate a variety of patterns. Three pat- 

 terns are shared by nine of the more frequently 

 occurring taxa (Table 7). These involve 1) a 

 group formed by anchoveta and three coastal 

 forms; 2) a group formed by one myctophid and 

 two other mesopelagic species; and 3) a species 

 pair consisting of sardine and a myctophid. An- 

 other species pair (two myctophids) can be formed 

 if the 1973 and 1983 abundances of T. mexicanus 

 are adjusted. 



Group I includes anchoveta, Normanichthys 

 crockeri, Blenniid D, and Sebastes sp. (Table 7). 

 There is a significant concordance among these 

 species as to years of highest (1966 and 1973) and 

 lowest (1965 and 1983) abundance (W = 0.69, 

 P < 0.01). The abundance rankings of anchoveta 

 and A'^. crockeri (p = +0.79) and of Blenniid D and 

 Sebastes (p = +0.88) are significantly correlated 

 (P < 0.01). None of the correlations between spe- 

 cies of the two pairs are significant due to differ- 

 ences in 1967-68 vs. 1970-72 relative abun- 

 dances. 



The three Group II species, Diogenichthys later- 



12 



