Myers and Barrowman: Is fish recruitment related to spawner biomass? 



721 



range in observed spawner abundance and provides 

 no evidence for our hypotheses. 



Within the Perciformes, the freshwater Percidae, 

 represented by perch of the genus Perca, and wall- 

 eye and pikeperch of the genus Stizostedion, provide 

 moderate evidence for the three hypotheses only 

 when there is a very wide range of observed spawner 

 abundance. However, for most of the marine species 

 of the order Perciformes (e.g. the Scombridae, the 

 mackerel and tunas, and the Sparidae, the sea 

 breams) there was very strong evidence for all three 

 hypotheses. One explanation for this pattern is that 

 freshwater species for which we had data may have 

 been less subject to overexploitation, but the ques- 

 tion certainly deserves further study. 



The order that showed the weakest amount of the 

 relationship between the abundance of spawners and 

 subsequent recruitment was the flatfish, i.e. the 

 Pleuronectiformes. There was evidence for this rela- 



tionship with both Pleuronectidae and Soleidae in 

 all the tests for wider ranges in spawner abundance, 

 i.e. the P-values in Table 2 were less than 0.5; how- 

 ever, these relationships were not statistically sig- 

 nificant. The relatively weak relationship for flat- 

 fish may be caused by the strong density-dependent 

 mortality for these populations (Myers and Cadigan, 

 1993; lies, 1994). Furthermore, many of these popu- 

 lations have juvenile nursery grounds in regions 

 where exploitation cannot take place. For these rea- 

 sons, the range of spawner abundance has been rela- 

 tively narrow, which reduces our ability to detect any 

 relationship. 



For the salmonids included in this analysis, large 

 year classes almost always are associated with high 

 spawner levels. This conclusion is true for the pink, 

 chum, sockeye, and Atlantic salmon for each life-stage 

 transition considered (Table 2). Our conclusion differs 

 from that of Larkin ( 1977 ), who stated that for the Pa- 



