Panmixia in a Critically Endangered Fish: The Totoaba (Totoaba macdonaldi) in the Gulf of California

Abstract

Conservation of the evolutionary legacy of endangered species is a key component for long-term persistence. Totoaba is a long-lived fish endemic to the Gulf of California and is considered critically endangered. There is currently a debate concerning its conservation status and whether it can be used as a fishery resource. Unfortunately, basic information on biological and genetic population structure of the species is lacking. We sampled 313 individuals and employed 16 microsatellite loci and 3 mitochondrial DNA markers (16S, 547 pb; COI, 619 pb; control region, 650 pb) to assess population structure and demography of totoaba in the Gulf of California, with samples from locations that encompass nearly all of its recognized geographic distribution. We could not reject a hypothesis of panmixia for totoaba, using nuclear or mitochondrial markers. Demographic analysis of mtDNA suggests a sudden population expansion model. The results have important implications for totoaba conservation because poaching is a significant conservation challenge and could have additive negative effects over the single population of totoaba in the Gulf of California.

Phylogeography, Population Structure, and Historical Demography of Black Drum in North America

“…This mutation rate has been previously used to construct Bayesian skyline plots for another sciaenid, the Totoaba Totoaba macdonaldi (Valenzuela‐Quiñonez et al. 2016). We performed four separate MCMC runs for 50 million generations, sampled every 1,000th generation.…”

Nuevas características en distribución espacial, edad y crecimiento de la especie protegida Totoaba macdonaldi en el Golfo de California

“…Rowell et al (2008b) validate the relationship between temperature, water oxygen isotope composition (δ 18 O) and otolith δ 18 O. Other studies focus on the distribution of juveniles and its relationship with salinity (Valdez-Muñoz et al, 2010), the rate of rebound estimate for totoaba (r 2M = 0.055) (Márquez-Farías and Rosales-Juárez, 2013), and recently, genetic diversity and population dynamics (Valenzuela-Quiñonez et al, 2014, 2016. Nevertheless, some basic questions remain valid, such as which is the distribution, age structure and individual growth of this species today?…”

“…The "F" test was applied to the model and the "Student t" test was applied to b values under the hypothesis that b = 3 (isometric growth) (Sparre and Vennema, 1997). Length-weight data were pooled across sample sites, as sample size was small for some localities (Table 1); in addition, all specimens were considered as belonging to a single population in the Gulf of California (Valenzuela-Quiñonez et al, 2016).…”

“…In this study, it is clear that the age distribution of the fish sampled in the Biosphere Reserve region (Upper Gulf ) is the best representation for the totoaba population, showing ages spanning from 0 to 19 years. When the data were pooled, since totoaba is considered to be a panmictic population from the Gulf of California (Valenzuela-Quiñonez et al, 2016), a truncated population showing the absence of some adult age classes and biased towards juveniles was observed. This may indicate the impact of fishing pressure years ago, but may also reflect the limitations of sampling, associated with the difficulty to access recruitment…”

Untitled

“…In recent years, research on different aspects of the totoaba was intensified [35,[37][38][39][40][41][42][43]. The unexpected catch of two five-foot-long adult totoaba, caught in East Cape, near to San José del Cabo (its maximum adult range previously known extends southward only to about Bahia de Los Angeles on the Baja coast.…”