Page 9 - Ragonese_Bianchini_1996

S. Ragonese, M.L. Bianchini l Fisheries Research 26 ( 1996) 125-137 133

20.0
a)
- t,=l.O (y) ',
t,=l.S (y) ;

15.0

3
·s
..
...
t 10,0
.:.
" c.
:9 /
" ;;: /
/
5.0
*
/
/
o. o
0,0 0.3 0.6 0,9 1.2 1.5 L8

20.0
- t,=l.O (y) b)
t,=l.5 (y)

15,0
3
·~
...
t
.:.
" c. 10.0
..Q
"ii / *
;;: /
/
/
5.0 /
l

0.0
~--._--~--~--~--~--~
0.0 0.3 0.6 0,9 u 1.5 1.8
Fishing mortality (F /year)

Fig. 5. Yield-per-recruit curves for M"= 0.8 ( above) or M,= 0.5 (below) with fc = l year and t~= L5 year, for
Aristeus antennatus. The asterisk denotes the current leve! of exploitation according to the growth and mortality
estimates.

As a matter of fact, the curve fits the data quite well and i t is worth noting that the MIX-
integrated growth estimates fall inside the bivariate ellipse of confidence of the ELEFAN-
1 bootstrapped estimates (Fig. 3) .
Concerning the annua! total mortality (Z), Heincke' s method gives values of 0.4 an d l. l
for the summer and autumn survey respectively, whereas the length-converted catch curve
yields a higherrange ofvalues ( 1.3-1.5). The spring value (Z = 0.4) seems too lo w, whereas