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Snappers are opportunistic carnivores with a leading role in energy flows between trophic interactions within tropical ecosystems. In the southern Gulf of Mexico, the few reported trophic-structure models are based on snapper stomach content data from other geographic regions (e.g. Atlantic coast of United States, northern Gulf of Mexico, Caribbean Sea and Brazil). To optimise the reliability of these models, we present new information on the diet composition of two commercially important species: lane snapper Lutjanus synagris and yellowtail snapper Ocyurus chrysurus. From January 2008 to 2009, the stomach contents of 1,074 L. synagris and 1,516 O. chrysurus were collected from three fishing sites off the northern coast of Yucatan, Mexico. Contents were analysed using frequency, number and weight of the identified prey species. A three-level, nested PERMANOVA analysis was used to assess differences between the potential prey and their biomass using the factors of snapper species, fishing site and climate season. Multidimensional scale (MDS) and SIMPER analyses were run to establish dissimilarity within the discriminating factors. The main food items found in the L. synagris diet were Brachyura, Penaeioidea and unidentified shrimps. Penaeioidea were the most abundant items in the O. chrysurus diet. Prey biomass analysis revealed a dissimilarity in diet composition between the two snapper species, as well as between fishing sites and climate seasons. The principal discriminatory prey categories were Brachyura, Penaeioidea, Osteichthyes, with Caridea and unidentified shrimps accounting for slightly smaller proportions. The results confirm the trophic position of these two sympatric snappers, showing that each plays a different trophic role in the ecosystem of the northern coast of the Yucatan Peninsula. [ABSTRACT FROM AUTHOR]

The three most important grouper fishery species in southern Gulf of Mexico, Epinephelus morio, Mycteroperca bonaci and Mycteroperca microlepis, do not have life history parameters data reported such as growth, age and natural mortality essential to management. Individuals from the three species were captured in the Campeche Bank (CB) at different times from 1988 to 2001. Sagittae were thin‐sectioned to count annuli: n = 1081 for E. morio, n = 920 for M. bonaci and n = 251 for M. microlepis. Otoliths from the three species exhibited successive opaque and translucent bands deposited with an annual frequency, occurring between January and April for E. morio and M. bonaci, and between January and March for M. microlepis. Estimated age in the three grouper species ranged from 0+ to 20 years. The most frequent ages were 7–10 years for E. morio and 8–12 years for M. bonaci and M. microlepis. The von Bertallanfy Growth Function model parameters (L∞, K and t0) were consistent with reported growth patterns for Epinephelidae family species, as established by growth performance Ф' (near 3). The CB groupers appear to reach maximum ages over 13 years with K values between 0.09 and 0.12 year−1, indicating all three studied species displayed relatively slow growth rate and medium longevity. Lifespan values ranged from 13 to 33 years for E. morio, from 18 to 30 years for M. bonaci and from 17 to 33 years for M. microlepis. A50 was 6.1 years for E. morio and 5.5 years for both M. bonaci and M. microlepis. Age at which all females were mature was 8 years for M. bonaci and 10 years for E. morio and M. microlepis. P50 was 9.3 years for E. morio, 13.6 years for M. bonaci and 11.6 years for M. microlepis. Age at which 100% of individuals were male was 13 years for E. morio, 19 years for M. bonaci and 15 years for M. microlepis. Values of M at age exhibited an exponential decrease with age for all three species, but overall values were 0.13 year−1 for E. morio, 0.14 year−1 for M. bonaci and 0.17 year−1 for M. microlepis. For the three species size at age varied by geographical distribution area, but particularly for E. morio the discrepancy in average size between published studies may be the consequence of the fishing effort exerted on the stock and/or the lack of regulation for the fishery prior to 2001; after this stock biomass fell below the reference limit point and was declared overexploited. Resource managers could use the information provided in this study as a reference, representing pre‐overexploitation values, to evaluate the current status of these populations and ensure sustainable management actions for the CB grouper fisheries. [ABSTRACT FROM AUTHOR]

In tropical regions, temperature is the fundamental environmental factor controlling the reproduction-related physiological activities of fish. Tropical fish are particularly sensitive to climate change since they develop in a relatively stable thermal environment. A review was done to assess the potential effect of temperature rise on reproduction and population structure in the commercially important hermaphrodite grouper and wrasse species, and in gonochoric snapper species in the southern Gulf of Mexico. Temperature increase can disturb the aromatase synthesis and/or activity, which can affect the reproductive cycle and sexual differentiation in all studied species and the sexual inversion process in sequential hermaphrodites. Moreover, a mistiming or discontinuity in spawning seasonality could occur, with an alteration in the sex ratio in favor of males and a consequent reduction in populations' fecundity. Furthermore, if the level of fishing exploitation enhances species' sensitivity to environmental changes, then the stock of red grouper Epinephelus morio would be more affected by temperature increases than other species because it is the only fish population in the Campeche Bank currently assessed as overexploited. [ABSTRACT FROM AUTHOR]

Based on their morphological and genetic similarity, several studies have proposed that Lutjanus campechanus and Lutjanus purpureus are the same species, but there is no confirmed consensus yet. A population-based study concerning otolith shape and genetic analyses was used to evaluate if L. campechanus and L. purpureus are the same species. Samples were collected from populations in the southwestern Gulf of Mexico and the Venezuelan Caribbean. Otolith shape was evaluated by traditional and outline-based geometric morphometrics. Genetic characterization was performed by sequencing the mtDNA control region and intron 8 of the nuclear gene FASD2. The otolith shape analysis did not indicate differences between species. A nested PERMANOVA identified differences in otolith shape for the nested population factor (fishing area) in morphometrics and shape indexes (p = 0.001) and otolith contour (WLT4 anterior zone, p = 0.005 and WLT4 posterodorsal zone, p = 0.002). An AMOVA found the genetic variation between geographic regions to be 10%, while intrapopulation variation was 90%. Network analysis identified an important connection between haplotypes from different regions. A phylogenetic analysis identified a monophyletic group formed by L. campechanus and L. purpureus, suggesting insufficient evolutionary distances between them. Both otolith shape and molecular analyses identified differences, not between the L. campechanus and L. purpureus species, but among their populations, suggesting that western Atlantic red snappers are experiencing a speciation process. [ABSTRACT FROM AUTHOR]

The relationship between total length and total weight (LWR) of four commercial species of finfish captured in the southern Gulf of Mexico (Lachnolaimus maximus, Ocyurus chrysurus, Mycteroperca bonaci, and Mycteroperca microlepis) was estimated. Two of these species are captured in the region by the small-scale fleet, while the other two are targeted by small-scale and semi-industrial fleets using harpoons, handlines, and long-lines. For the assessment, the organisms were sampled at the landing decks in the study area in two periods: 1996-1999 (semi-industrial fleet) and from April 2017 to May 2018 (small-scale fleet). A total of 2780 individuals were sampled which 2775 individuals were used to obtain LWR functions. The four species showed negative allometric growth with b < 3 for the 2017-2018 period, two species showed positive allometric growth with b > 3 for the 1996-1999 period. This type of information is an important input for the stock assessment of these species that support important fisheries in the zone and are under high fishing pressure levels. [ABSTRACT FROM AUTHOR]

Hogfish Lachnolaimus maximus (Walbaum, 1792) is the largest labrid in the Atlantic and a commercially important fish. In previous research, this fish has been defined as a monandric protogynous hermaphrodite, although characterization of hermaphroditism is particularly challenging in labrids. Examination of testicle structure is not always a wholly trustworthy method for distinguishing between diandric species (those with primary and secondary males) and monandric species (only secondary males). In some diandric species, morphological differences in the testes do not occur between primary and secondary males despite functional diandry. The presence of individuals with inactive bisexual gonads and/or of inactive males smaller than the minimum size of sexual maturation is a more dependable criterion for identifying diandry. A histological analysis of the gonads of 1,975 L. maximus specimens (10.3-47.4 cm fork length, FL ) from the southern Gulf of Mexico was done. Some individuals were identified that were larger than the size at first maturity (N = 20,24.8-33.5 cm FL) and had ovotestes atypical of a monandric species. These ovotestes had an internal morphology like ovaries, consisting mostly of inactive ovary tissue in lamellar structure, as well as limited development of active testicular tissue in crypts inside the gonad wall and/or in lobules beneath the gonad wall. Considered to be “bisexual" gonads, their origin and function were evaluated based on published data. Lachnolaimus maximus could be defined as a diandric species if males can differentiate indirectly by sexual inversion of functional females (postmaturational secondary males) or by direct development from the “bisexual" stage (prematurational secondary males). However, no inactive bisexual individuals or inactive males smaller than the size at first maturity were observed. In addition, population structure and overall sex ratio were typical of a monandric protogynous species. The possibility that L. maximus could exhibit diandric hermaphroditism therefore remains hypothetical. [ABSTRACT FROM AUTHOR]

High rates of undersized catch and discard mortality are common in fisheries for Red Grouper Epinephelus morio in the Gulf of Mexico and Atlantic Ocean. Reducing undersized catch rate in these fisheries requires more effective regulation of the minimum size limit (MSL). One potential method is to regulate hook selectivity for target species. Three circle hook sizes (11/0, 12/0, and 13/0) were tested to assess the effect of hook size on Red Grouper catch rate and size in the shallow waters of the Yucatan Peninsula coast, which is the primary fishing zone for the region's small‐scale grouper (family Epinephelidae) fishery. Red Grouper was always the numerically dominant species in catches (76–81%) for all hook sizes. Hook size did not affect mean catch rate. Significantly longer fish were caught in the 13/0 hook size treatment than in the 11/0 and 12/0 treatments, which did not differ. Nonetheless, when considering the MSL regulation applicable in Mexico's Red Grouper fishery (36.3 cm TL), high percentages of undersized Red Grouper were still caught, regardless of hook size. The hook sizes required in the Yucatan small‐scale fishery (10/0–12/0) provide little if any improvement in Red Grouper MSL regulation. Real improvement would require the effective release of undersized fish as well as a reduction in the number of undersized specimens caught and in potential cryptic sources of fish release mortality (e.g., barometric trauma). Furthermore, the current applicable Red Grouper MSL only really attempts to control growth overfishing and ignores recruitment overfishing. Received December 22, 2014; accepted September 3, 2015 [ABSTRACT FROM AUTHOR]

Describing patterns of connectivity among populations of species with widespread distributions is particularly important in understanding the ecology and evolution of marine species. In this study, we examined patterns of population differentiation, migration, and historical population dynamics using microsatellite and mitochondrial loci to test whether populations of the epinephelid fish, Gag, Mycteroperca microlepis, an important fishery species, are genetically connected across the Gulf of Mexico and if so, whether that connectivity is attributable to either contemporary or historical processes. Populations of Gag on the Campeche Bank and the West Florida Shelf show significant, but low magnitude, differentiation. Time since divergence/expansion estimates associated with historical population dynamics indicate that any population or spatial expansions indicated by population genetics would have likely occurred in the late Pleistocene. Using coalescent-based approaches, we find that the best model for explaining observed spatial patterns of contemporary genetic variation is one of asymmetric gene flow, with movement from Campeche Bank to the West Florida Shelf. Both estimated migration rates and ecological data support the hypothesis that Gag populations throughout the Gulf of Mexico are connected via present day larval dispersal. Demonstrating this greatly expanded scale of connectivity for Gag highlights the influence of “ghost” populations (sensu Beerli) on genetic patterns and presents a critical consideration for both fisheries management and conservation of this and other species with similar genetic patterns. [ABSTRACT FROM AUTHOR]

Despite its commercial importance and high vulnerability to fishing impact, little is known about the reproductive biology of the Tiger Grouper Mycteroperca tigris, an aggregative spawner. We studied the key reproductive parameters of this species in the southern Gulf of Mexico, where the grouper fishery is generally in decline. The smallest mature female measured 31.4 cm FL, and length at which maturity was attained in 50% of females (L50) was 34.2 cm FL. Tiger Grouper are protogynous hermaphrodites, and the estimated length at which 50% of females had changed sex was 51.9 cm FL. Spawning season lasted from February to June, with a spawning peak observed in April. Most of the actively spawning females were collected 7-14 d after the full moon in April and May. Females exhibited continuous, asynchronous oocyte development and batch release of mature oocytes. During April-June, estimated spawning interval varied monthly from 1.8 to 4.3 d (mean = 2 d). Due to the species' indeterminate fecundity, we estimated batch fecundity, which ranged from 84,119 to 1,032,578 oocytes (mean ± SE = 417,102 ± 34,826 oocytes). Conservation status of the Tiger Grouper in its distribution area is currently unclear. Based on the observed maximum sizes for both sexes and the size of sexual transition, the southern Gulf of Mexico Tiger Grouper population may be healthier than some Caribbean Sea populations. Current and potential measures for regulating this fishery resource in the southern Gulf of Mexico are discussed. [ABSTRACT FROM AUTHOR]

Despite its commercial importance and high vulnerability to fishing impact, little is known about the reproductive biology of the Tiger Grouper Mycteroperca tigris, an aggregative spawner. We studied the key reproductive parameters of this species in the southern Gulf of Mexico, where the grouper fishery is generally in decline. The smallest mature female measured 31.4 cm FL, and length at which maturity was attained in 50% of females (L50) was 34.2 cm FL. Tiger Grouper are protogynous hermaphrodites, and the estimated length at which 50% of females had changed sex was 51.9 cm FL. Spawning season lasted from February to June, with a spawning peak observed in April. Most of the actively spawning females were collected 7–14 d after the full moon in April and May. Females exhibited continuous, asynchronous oocyte development and batch release of mature oocytes. During April–June, estimated spawning interval varied monthly from 1.8 to 4.3 d (mean = 2 d). Due to the species' indeterminate fecundity, we estimated batch fecundity, which ranged from 84,119 to 1,032,578 oocytes (mean ± SE = 417,102 ± 34,826 oocytes). Conservation status of the Tiger Grouper in its distribution area is currently unclear. Based on the observed maximum sizes for both sexes and the size of sexual transition, the southern Gulf of Mexico Tiger Grouper population may be healthier than some Caribbean Sea populations. Current and potential measures for regulating this fishery resource in the southern Gulf of Mexico are discussed. [ABSTRACT FROM AUTHOR]

The article examines the diet composition of young black grouper from the coastal nursery areas of the Yucatán Peninsula, Mexico. Groupers depend from their habitat in search for food and shelter. They tend to have secretive habits, occupying caves, crevices and ledges. Groupers' Yucatá Peninsula habitat mainly consists of sandy-rocky bottoms, which is different from that described for Atlantic and eastern Gulf of Mexico coastal waters.

Growth stanzas or abrupt changes in growth rates are present throughout the life span of fish. Identifying growth stanzas will help to adequately described growth taking into account that fishes are indeterminate growers. In this study, we used length-weight (L-W) relationships to analyze the growth stanzas in the Grouper-Snapper complex of Southern Gulf of Mexico. For this, the type of sexuality, sex and different sexual maturity phase were considered in the analyses of three species of gonochoric Snappers (Lutjanidae) and six species of protogynous hermaphrodite Groupers (Epinephelidae). Welch ANOVA tests were carried out to determine the existence of differences in length and weight between juveniles and adults per sex. According to the observed differences, L-W relationship parameters (a and b), standard error (SE b) and coefficients of determination (R²) were calculated for all species separately by sex and sexual maturity phase. Snappers' juvenile-females b-value ranged from 2.44-2.77, juvenile-males from 2.16-2.94, adult-females from 2.63-2.80 and adult-males from 2.63-2.98. Groupers' b-value ranged for juvenile-females 2.66-3.20, adult-females from 2.73-3.31 and for adult-males 2.93-3.29. For each relationship b-value was t-tested (t-Student) to explore differences from the allometric coefficient (b=3), which indicated changes in body form. Hypothesis test, for regression slopes (b) between Snappers' juvenile-females vs. adult-females and juvenile-males vs. adult-males and Groupers' juvenile-females vs. adult-females and adult-females vs. adult-males, indicated different growth stanzas related to gonadal development for Snappers, and to gonadal development and sex change in Groupers. The identification of growth stanzas is crucial to avoid an overestimation or misleading growth rate which is used in fisheries management to establish some target reference points, such as maximum sustainable yield or yield-per-recruit. [ABSTRACT FROM AUTHOR]