1. Trends in relative investment of energy in growth and/or reproduction by Peruvian hake Merluccius gayi peruanus from 1972 – 2004: an issue of length dependence Authors: Michael Ballón, Claudia Wosnitza-Mendo, Arnaud Bertrand, Jacqueline Palacios, Humberto Olivera, and Renato Guevara-Carrasco Presented by : Michael Ballón Instituto del Mar del Peru, Project INCOFISH

2. OVERVIEW Introduction Objective Materials and Methods Results and Discussion Conclusions

3. Significance of hake Distribution Main factors that have affected the hake population sardine and anchovy regime El Niño Overfishing 40 cm  25 cm Current situation New regulations (2002) were set up based on a single species approach (IMARPE) The stock still far from recovery Why? Introduction

4. Objective Main question: How has hake reacted physiologically to the fishing pressure and the physical environment? Clarifying the effects. Reducing uncertainty about: Natural Mortality and Recruitment Success Hake physiological responses

5. Materials and Methods Biological data: 52106 Female hakes sampled from 1971-2004 from Paita port Total body weight(W) Total length(L) Gonad weight(Wg) Stomach weight(Ws) Biological Indices Fulton's condition factorK = W.L -3 Gonadosomatic index GI = Wg.W -1 Fullness indexFI = Ws.W -1 Physical environment and time Paita sea surface temperature anomaly (SSTA) Year-Month(YM) Time series (1971-2004) Condition factor Gonadosomatic index

6. Results and Discussion…time series

7. Long term Upward trend in condition factor Downward trend in reproduction activity Results and Discussion…time series Short term Negative impact of El Niño In both: Fish condition and reproduction

8. Results and Discussion…? What are the factors that influence fish condition and maturation proccess?

9. Materials and Methods Biological data: 52106 Female hakes sampled from 1971-2004 from Paita port Total body weight(W) Total length(L) Gonad weight(Wg) Stomach weight(Ws) Biological Indices Fulton's condition factorK = W.L -3 Gonadosomatic index GI = Wg.W -1 Fullness indexFI = Ws.W -1 Physical environment and time Paita sea surface temperature anomaly (SSTA) Year-Month(YM) Generalized Additive Model GAM (1980 -2004) Large hakes (35-50 cm) Small hakes (20-35 cm) Condition factor K according to GI+FI+SSTA+YM Gonadosomatic index GI according to K+FI+SSTA+YM

10. Fullness index Results and Discussion…GAM models Condition factor: K according to GI+FI +SSTA+YM Large hake (35-50cm) Small hake (20-35cm) Gonadosomatic index “Condition factor” Gonadosomatic Index: GI according to K+FI +SSTA+YM During the spawning season there is a starving process. Fecundity depends more on the initial condition factor than on the food intake during the spawning season. Better condition More food Better condition Higher Fecundity Starving

11. Results and Discussion… “Condition Factor” “Gonadosomatic index” Poor condition + spawning  high mortality Large hake invest more energy in reproduction than small hake Large hake disappeared during the El Niño 1992-93 and 1997-98 Large Small Large Small SSTAnomaly EL Niño _ +

12. RESULTS and DISCUSSION…long term “Condition factor” “Gonadosomatic index” Large hake (35-50 cm) Small hake (20-35 cm) “Gonadosomatic index” “Condition factor” ? Why small hake spent their energy reserves in reproduction and large hake do not, although the latter has a higher condition factor ?

13. RESULTS and DISCUSSION…long term Low reproduction could be expected when biomass is close to the carrying capacity level HOWEVER hake biomass has been at a low level from the late 1990s onwards Size at first maturity has reduced in the last decades (recovering SSB) AND at the same time large hake has reduced reproduction activity  That is not a logical density-dependent effect Is this a density-dependent effect?

14. RESULTS and DISCUSSION…long term 35 +_ 2 cm +_ 25 +_ 2 cm 20 Female proportion Years Female propotion estimated from commertial landings Paita Sex proportion from 80% males to 80% females Lack of males for large hake ( >35 cm) Low fertilization rate Low stimulation for the spawning act

15. Conclusions