Pablo del Monte-Luna

Climate Change Effects on Aquatic Ecosystems and the Challenge for Fishery Management: Pink Shrimp of the Southern Gulf of Mexico

Ecosystems that change through time impose new scientific challenges for fisheries management advice. We present a case study to illustrate our view on how to face such challenges. The Pink Shrimp fishery in the Southern Gulf of Mexico has collapsed. Annual yields were about 24,000 metric tons during the mid-1950s to early 1970s; currently, they are about 1,200 metric tons. Overfishing was assumed as the main cause, but single-species models failed to provide the advice necessary for recovery. An inverse relationship between stock abundance and temperature was demonstrated, and a decline in recruitment and primary production (since 1970s) was observed. We constructed a trophic model for the ecosystem using Ecopath with Ecosim, incorporating the annual mean anomaly of the Atlantic Multidecadal Oscillation as a climate change index to force primary production. Signals were propagated throughout the food web, and biomasses were simulated for the period of 1956 to 2011. Ecosystem changes were estimated with t...

Vulnerability and body size : tetrapods versus fish

The relationship between body size and risk of extinction has been the focus of much recent attention; however, it has only been stated for a few groups inhabiting restricted areas. Based on the IUCN list and other public records, we suggest that the relationship between vulnerability and body size is a trend among all vertebrates, especially tetrapods. In the case of fish, our results show that body size may be subordinate to another factor that we named concealment. Other plausible explanations about this difference could be the human preference for large terrestrial vertebrates and/or the inappropriateness of the current IUCN listing criteria for fish species.

Putative extinction of two sawfish species in Mexico and the United States

All species of sawfish are listed by the International Union for the Conservation of Nature (IUCN) as endangered or critically endangered. In fact, the smalltooth sawfish Pristis pectinata, and the largetooth sawfish Pristis pristis, have been declared to be regionally and locally extinct from the US Atlantic coast and the Gulf of California, Mexico, respectively, likely due to overfishing. However, here we dispute these claims by illustrating how lack of existence of a given species within a region can be misconstrued as evidence for extinction. Todas as especies de peixe-serra sao qualificadas pela Uniao Internacional para a Conservacao da Natureza como ameacadas ou criticamente ameacadas de extincao. De fato, o peixe-serra-de-dentes-pequenos, Pristis pectinata, bem como o peixe-serrade-dentes-grandes, Pristis pristis, tem sido declarados como regionalmente e localmente extintos da costa atlântica dos EUA e do Golfo da California e Mexico, respectivamente, provavelmente devido ao excesso da pesca. No entanto, aqui pretendemos questionar estas extincoes ilustrando como a falta de evidencias da existencia de uma especie em uma regiao pode ser mal interpretada como evidencia de extincao.

Patrones históricos y escenarios térmicos futuros en mares mexicanos

Into different areas (e.g., academic, public) predictions of climate as part of the process of decision-making are required. Despite such information need, the inconsistency of global models to predict the state of the climate in small scales (regions) is widely recognized. Considering this, we tested predictions of sea surface temperature (SST) in 10 marine regions off the coast of Mexico. Using classification and regression trees, Mexican coastal states were grouped accordingly to their similarity in instrumental records of air temperature (AST). Such AST groups were considered explanatory variables together with regional climatic scale indices (e.g., Pacific Decadal Oscillation, PDO). Historical patterns of change (period, amplitude and phase) of AST and climate indices were characterized, and then its relationship with SST was analyzed using generalized additive models (GAM). The SST response to climatic scenarios was evaluated with 3 different forcing criteria. The GAM models showed significant fits and relatively high values of R² and deviance. Projections of regional climate variability showed substantial differences in comparison to the monotonic increase in SST global models outputs. The re-scaling strategy applied in this work for Mexican seas surface temperature, proved to be useful to integrate the historical variation with different forcing criteria.

Statistical inference for extinction rates based on last sightings

Rates of extinction can be estimated from sighting records and are assumed to be implicitly constant by many data analysis methods. However, historical sightings are scarce. Frequently, the only information available for inferring extinction is the date of the last sighting. In this study, we developed a probabilistic model and a corresponding statistical inference procedure based on last sightings. We applied this procedure to data on recent marine extirpations and extinctions, seeking to test the null hypothesis of a constant extinction rate. We found that over the past 500 years extirpations in the ocean have been increasing but at an uncertain rate, whereas a constant rate of global marine extinctions is statistically plausible. The small sample sizes of marine extinction records generate such high uncertainty that different combinations of model inputs can yield different outputs that fit the observed data equally well. Thus, current marine extinction trends may be idiosyncratic.

Approaching the Potential of World Marine Fisheries

Abstract During the last 60 years, the world marine fisheries potential has been estimated between 22·106 tons and 1 400·106 tons. However, there are no certain indications of when and with what probability such potential will be reached. By fitting a logistic curve to the observed world marine catch, corrected for discards and illegal, unreported and unregulated fishing, here we calculated that such potential stands between 132·106 tons and 153·106 tons and might be achieved as soon as the year 2027, with 95% confidence.

Macro-Scale Patterns in Upwelling/Downwelling Activity at North American West Coast.

The seasonal and interannual variability of vertical transport (upwelling/downwelling) has been relatively well studied, mainly for the California Current System, including low-frequency changes and latitudinal heterogeneity. The aim of this work was to identify potentially predictable patterns in upwelling/downwelling activity along the North American west coast and discuss their plausible mechanisms. To this purpose we applied the min/max Autocorrelation Factor technique and time series analysis. We found that spatial co-variation of seawater vertical movements present three dominant low-frequency signals in the range of 33, 19 and 11 years, resembling periodicities of: atmospheric circulation, nodal moon tides and solar activity. Those periodicities might be related to the variability of vertical transport through their influence on dominant wind patterns, the position/intensity of pressure centers and the strength of atmospheric circulation cells (wind stress). The low-frequency signals identified in upwelling/downwelling are coherent with temporal patterns previously reported at the study region: sea surface temperature along the Pacific coast of North America, catch fluctuations of anchovy Engraulis mordax and sardine Sardinops sagax, the Pacific Decadal Oscillation, changes in abundance and distribution of salmon populations, and variations in the position and intensity of the Aleutian low. Since the vertical transport is an oceanographic process with strong biological relevance, the recognition of their spatio-temporal patterns might allow for some reasonable forecasting capacity, potentially useful for marine resources management of the region.