BEACHAM and STARR: POPULATION BIOLOGY OF CHUM SALMON 



Table 5.— Correlation matrix for theoKK-to-fry 

 survival model. Variables are listed in the text. 



c E 



■- CD 

 3 Q. 



<v 



1=1 



cut 



ra = _ 



£. £ >< 



to »-■ —  



CD _ 



5 O 





— C« 



3 >- o 

 < a* 



*23 



z o 



co 



° E 



IE 

 I* 



C/) en 

 



■D . 

 O co 

 O Qj 



^ocococomcomco<x>T-T)-cM «f 



'J(D©0)i-t-i/)COCDSOt-tJ; T 



i-CNJocococsi^csjco^^cvi'^ ^ 



(bcococooiiriioco^Trsoico 

 cocor^o>r^CNjCNjcococococoin 



NC\JO)OOin^oscpoo)co^ 

 uScbco^^t^r^cbi-cbcb^oS 



C\J CNJ 



i- t- m 



OlfilDNO)OmO)'tNN^^)<P ** 



CM COC^ajcOl^^oS^r^OTj-r^ W N 



COOIOJOCDCNJCVJITNNOOOCNJ CM CNJ 



i-CD'-'-COCDCNjm'--^-CNJC7)- , <3- o :m 



r^mmcMcDoo^tcDi-ococDm co 



co-tNCvjoiroinouioocON r*- o> r- 

 cbroOi-T-NcotDcosi-piJif) cb cb co 



*- CM CM v- T-CNJCMr-i- 



t-oroi-onNs^onno cd 



CJ)i-CO'tNC\I^t(DCMT-(Ot-ir) o 



Oi-OCVJr-r-OOJr-r-O'-O l^ 



cO'-CNjcnoooo^-oicDCNjr-T-o m 



cbcbcbcrJoSinihcri'^-^r^oSco o 



cocor^Oh-CMCMcococococoin *- 



cMTj-i-cNjincTicooD^incocNjcD cnj 



lfilT)CO'-'-CONSOI/)in'-i- i-CO^ti-i-'* 



cT>^incNJcT>cTioincDcbcNJotb cm i*^ in rr o o> 



couocotpncNjomTj-NCMinco 

 uSc\JTrc^c\iihoScNr-~ooodcT)0 



o cm ro »- f 

 co co ^r co CT) 



cvjiuomcnNtDNO^inoco »- r*- 



^u)coinco(DinoN^sncM cm *- cm co p in 



cNjCNJr^^r^c6crJr^oo^tco-<j : o a> ocin i 



SO)^^UO(DCOSSS(DCOt- Tt o »- CO N CD 



CNjCNjco-^-cOh-cocNjcDm'^-oco o> 'f o co co in 



ooooooooooooo o ooocoo 



OOOincOOO'-CDOCOCD'- CO CJ) CO CNJ o o 



cooqcoo)i/)(00)coioo)coin ^ co co o co s 

 co o r- m a) cd cm cm co in cm" co o *- m o i- oo co 



cotJ)Ocoonoo)ONi , ninO)wi-N(Os 



t-^i-CM»-CO(M'-i-COCMCM »- CO CNJ CM *- 



ooooooooooooo o ooooo 



ooooooooooooo o ooooo 



OOOOOOOOi-^f^-h-O CO CO N CO CD N 



tj-" o" ^r in in o cm cm" o" co" co a> co in" m" oo" co' cd n-* 



tDCO'-CNJCOCO'-CNIOOmsm CD co co co co w 



»-r-c\JcOt-^c\icocococoiOTr m cm m uo Tf n 



'-CMCO^mcDSCOOO'-CMCO Tf UO (DN CO O) 

 CDCDCDCOCOCDCDCDCDSNNN r- r-- r-- h- h- h- 

 0)0)<J)CJ)0)CJiO)CJ)CJ)ONO)0105 CJ) CJ> O") O) CT> O) 



There was a slight tendency for egg survival to 

 decline with increasing numbers of eggs de- 

 posited and this effect was enhanced by a cold 

 winter. Thus spawning escapement (egg deposi- 

 tion), rainfall, and temperature interact to pro- 

 duce variable freshwater survival. Fry-to-adult 

 survival was inversely correlated with egg-to-fry 

 survival (r = —0.62, n = 14, P<0.05), which sug- 

 gests a density-dependent response of chum 

 salmon fry survival. 



Age of Return 



Total returns from the 1961 through the 1974 

 chum salmon brood years have ranged from 

 180,000 to 1,930,000 fish (Table 4). The propor- 

 tion of the brood year returning at age 3 has 

 ranged from 4% to about 42%. To determine if the 

 mean age at maturity from a brood year was de- 

 pendent upon the total number of adults pro- 

 duced from that brood year, we regressed mean 

 age at maturity (in years) on total return (Fig. 5). 

 This regression produced: 



Mean age = 3.67 + 1.923 X 10" 7 Returns 



(n = 14) (4) 



where r — 0.63 ( P<0.05). The mean age at matur- 

 ity of a brood year increased as did the total num- 



200 400 600 800 1000 1200 1400 1600 1800 2000 



Tolo I cecums (» I0* 3 ) 



Figure 5.— Mean age of return of a brood year of chum salmon 

 versus its abundance. 



819 



