Management Strategy Evaluation

Research Summary

Mark has been involved in several projects on management strategy evaluation (MSE) and organised a workshop on management strategies for tuna in 2007. He believes that without a reasonable stock assessment model to use as an operating model for MSE, the benefits of the MSE process, outside identifying management objectives and accumulating knowledge about the system, is very limited. Therefore, Marks focus has been on developing and improving stock assessment models that could be used as operating models. Mark's masters thesis (Maunder 1993) involved a comprehensive management strategy evaluation including a range of harvest strategies and selectivity options, evaluated using econimic data. He was also involved in the inital management strategy work for rock lobster in New Zealand (Breen et al. 1994). Mark developed one of first multi-species MSEs, which included a protected species, though it was rather rudimentary (Maunder et al. 2000), but was involved in further improvements (Breen et al. 2003). He also worked on reviewing the state of the science in MSE (Schnute et al., 2007). He developed early methods on how to use Stock Synthesis as an operating model for MSE (Maunder, 2014), which has formed the basis for subsequent work by others including bigeye tuna (Zhu et al. 2015) Pacific bluefin, both which Mark has been involved in. Mark's team at the IATTC has also conducted MSE for dorado (Valero et al. 2017).  Mark is currently working with Haikun Xu to conduct MSE for bigeye tuna in EPO. 

Relevant Papers

Carruthers, T.R., Kell, L.T., Butterworth, D.D., Maunder, M.N., Geromont, H.F., Walters, C., McAllister, M.K., Hillary, R., Levontin, P., Kitakado, T. and Davies, C.R., 2016. Performance review of simple management procedures. ICES Journal of Marine Science: Journal du Conseil. 73(2): 64-482. https://academic.oup.com/icesjms/article/73/2/464/2614445

Mark N. Maunder. 2014. Management strategy evaluation (MSE) implementation in Stock Synthesis: application to Pacific bluefin tuna. IATTC Document SAC-05010b. https://www.iattc.org/GetAttachment/5a329fd8-2bbf-4969-87ae-3361b0471575/SAC-05-10b%20-%20Management%20Strategy%20Evaluation

Schnute, J.T., Maunder, M.N., and Ianelli, J.N. 2007. Designing tools to evaluate fishery management strategies: can the scientific community deliver? ICES Journal of Marine Science, 64: 1077–1084. https://academic.oup.com/icesjms/article/64/6/1077/616074

Breen, P.A.., Hilborn, R., Maunder, M.N., and Kim, S.W. 2003. Effects of alternative control rules on the conflict between a fishery and a threatened sea lion (Phocarctos hookeri). Can. J. Fish. Aquat. Sci. 60: 527-541. https://www.nrcresearchpress.com/doi/abs/10.1139/f03-046#.Xp4z_8hKjD4

Maunder, M.N., Starr, P.J. and Hilborn, R. 2000. A Bayesian analysis to estimate loss in squid catch due to the implementation of a sea lion Population Management Plan. Marine Mammal Science, 16(2): 413-426. https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1748-7692.2000.tb00933.x

CAPAM Workshop reports

Maunder, M.N. (compiled by) (2007). Report from the workshop on management strategies, IATTC, La Jolla, California (USA), 17-20 October 2006. 

Reports

Valero, J. L., Aires-da-Silva, A., Maunder, M. N., et al. 2017. Exploratory Management Strategy Evaluation (MSE) of Dorado (Coryphaena hippurus) in the Southeastern Pacific Ocean. (2017). IATTC Document SAC-08-06a(ii).

Zhu, J., Maunder, M.N., Aires-da-Silva, A., and Sung, Y-C. 2015. Preliminary Management Strategy Evaluation to Evaluate the IATTC Interim Reference Point. IATTC Document SAC-06-10b. 

Maunder, M.N. 2014. Management strategy evaluation (MSE) implementation in stock synthesis: Application to Pacific bluefin tuna. IATTC Stock Assessment Report 15: 100-117.

Breen, P., Kendrick, T., Starr, P.J. and Maunder, M.N. (1994) Results of the implementation of the rock lobster decision rule in 1994. New Zealand Fisheries Assessment Working Group Report 94/3.

Masters Thesis

Maunder, M.N. 1993. Optimising Harvest Strategies for the West Coast Snapper(Pagrus Auratus) Fishery.  Masters Thesis. University of Auckland.

ABSTRACT

A stochastic age structured model is used to investigate optimal harvest strategies for New Zealand’s west coast snapper (Pagrus auratus, Sparidae (Bloch and Schneider, 1801)) fishery. The model includes a Beverton-Holt recruitment model, age specific vulnerability including non-recruited ages, and separate commercial fishing periods. The model is fitted to biomass data from the fishery to estimate virgin biomass, virgin recruitment, current biomass and the steepness parameter for the Beverton-Holt recruitment model. This data is then used with the model to investigate the effects of different harvest strategies described by Hilborn's (1985) linear catch equation: $catch = intercept + slope * stock size$. The optimal strategy is identified as a threshold strategy with an escapement level of 4000 t and a harvest rate of $0.25\text{ y}^{-1}$. Optimal constant annual fishing rate and escapement strategies give very similar catches and are only 0.1% and 1.7% less than optimal, respectively. The optimal constant annual catch strategy performs poorly as expected and gives 15.4% less catch. The length at 50% escapement is varied to investigate its effect on optimal catch. An increase from the current length (31.3 cm) to 45 cm gives an increase in catch of 34.75%, but also increases average inter-annual variation in catch and fishery risk (effort). A decision rule used to constrain risk to the stock and fishery, estimates an increase in catch of 13.74%. However, the economic value is not increased because of the cost of fishing and smaller short term catches. A parameter and structural sensitivity analysis is carried out including a temperature-recruitment relationship, recruitment dependence on stock, biomass estimation error, commercial catch implementation, stochastic natural mortality, historical recreational fishing rate dependent on the human population, and vulnerability. Results show that constant annual catch strategies tend to be more sensitive than threshold strategies. For threshold strategies only average inter-annual variation in catch is sensitive, except where the steepness of the Beverton-Holt recruitment model is less than assumed ($h=0.75$ and $0.50$), which causes opportunity loss in catch and less biomass than expected.