Variations in growth, longevity and natural mortality for the protogynous hermaphroditic eightbar grouper Hyporthodus octofasciatus between the Indian and Pacific Oceans

Demographic profile of an overexploited serranid, the orange-spotted grouper (Epinephelus coioides), from northern Oman

“…Monandric protogyny occurs when males develop only from females (secondary males) through a transitional phase, whereas diandric protogyny involves 2 pathways for male development: directly from juveniles (primary males) or through sex change from mature females (Reinboth, 1967). To date, most grouper investigated in detail and that belong to the genus Epinephelus have been confirmed to be monandric hermaphrodites (Sadovy et al, 1994;Brulé et al, 2000;Pears et al, 2006;DeMartini et al, 2011;Wakefield et al, 2015). However, increasing evidence indicates that some species are diandric hermaphrodites, such as the catface grouper (Epinephelus andersoni) Colin (1995) confirmed gonochorism, with the potential for protogynous sex change, in the Nassau grouper (Epinephelus striatus).…”

“…What has emerged is increasing evidence that many exploited reef fish species have life history strategies of extended life spans, slow growth, and, in the absence of fishing, an accumulation of older individuals-strategies usually associated with species in temperate (10-25°C) and deep (>30 m) waters (Choat and Robertson, 2002;Pears et al, 2006;Wakefield et al, 2013Wakefield et al, , 2015. Stocks that have such traits present challenges for fisheries managers, especially in developing countries where life history information is rarely collected (Polunin et al, 1996), mostly because of a lack of funding.…”

“…However, a suite of life history strategies and certain behavioral traits make most species of grouper susceptible to overfishing. Life-history strategies include slow growth and late-onset reproduction (Manooch, 1987;Pears et al, 2006), long life spans (Manooch, 1987;Bullock et al, 1992;Grandcourt, 2005;Wakefield et al, 2015), complex and variable reproductive patterns (Shapiro, 1987;Fennessy and Sadovy, 2002;Rhodes and Sadovy, 2002) including sex change, while traits include a propensity to aggregate during spawning (Colin, 1992;Sadovy et al, 1994;Samoilys and Squire, 1994;Robinson et al, 2015;Tuz-Sulub and Brulé 2015), and a high degree of site fidelity (Zeller and Russ, 1998;Starr et al, 2007;Luckhurst, 2008).…”

“…Frequently published low values of natural mortality (M) for grouper indicate that harvesting levels should be set at less than 10% of the total biomass (Walters and Pearse, 1996;Coleman et al, 2000). However, low rates of M coupled with commonly cited low rates of growth can also lead to "growth overfishing" with resultant truncated size-distributions as fish are unable to grow to their maximum sizes (e.g.…”

“…Hermaphroditism in groupers can be expressed in 1 of 2 ways: as simultaneous, when individuals are capable of reproducing as both male and female, or sequential (the most common mode), when sex change is made from female to male (protogyny) (Smith, 1965;Shapiro, 1987;DeMartini et al, 2011;Wakefield et al, 2015). Protogynous populations can be further characterized on the basis of the sexual pathway of male development.…”