Mexico Fishery Research Articles

Reducing bycatch in the United States Gulf of Mexico shrimp trawl fishery with an emphasis on red snapper bycatch reduction

Bycatch, the capture of non-targeted species during commercial fishing, is a global problem that may require novel solutions. The nested cylinder bycatch reduction device (NCBRD), developed using laboratory behavioral studies (Parsons and Foster, 2007; Parsons et al., 2012), was herein evaluated for reducing bycatch in shrimp trawl fisheries and for its application in the U.S. Gulf of Mexico (GOM) fishery. We examined the efficacy of the NCBRD for retaining shrimp, for reducing total bycatch, and for reducing bycatch of juvenile red snapper (Lutjanus campechanus), a species that is presently over-fished in the GOM. Using paired trawling on-board leased, commercial fishing vessels, shrimp catch, total bycatch, and the catch of red snapper juveniles were compared from trawls equipped with an NCBRD and control trawls without. Depending upon configuration, trawls with an NCBRD captured about 46–100% of shrimp taken in controls, reduced total bycatch by 26–60% and, of particular note, reduced red snapper bycatch by about 50%. When catch rates were compared, 2.29 (±0.38 s.e.)snapper/h/trawl were taken with an NCBRD and 6.11 (±0.93 s.e.)snapper/h/trawl without, a highly significant (ANOVA, P=0.0032, F=9.39, d.f.=1, 64) effect. Finally, using only red snapper captured in control trawls, we observed a significant effect of depth on red snapper capture with decreasing numbers of red snapper captured with increasing depth. In waters south of Galveston shallower than about 55m, catch rates ranged from 4.5 to 23.4snapper/h/trawl and in deeper water ranged from 0.3 to 2.4snapper/h/trawl. We identified a highly significant relationship (P<0.001, R2=0.685) between red snapper catch and depth. We estimate that use of the NCBRD would reduce juvenile red snapper bycatch in the northern Gulf of Mexico by about 50%. These results suggest that the NCBRD may find application in trawl fisheries worldwide.

Arm Abnormality inOctopus hubbsorum(Mollusca: Cephalopoda: Octopodidae)

Octopus hubbsorum Berry, 1953 occurs in a wide region of the oriental tropical Pacific. This is the principal target species in the octopus fisheries in Mexico. A female with abnormally bifurcated second arm was collected from an artisanal fishery in Puerto Angel, Oaxaca, Mexico.

Variabilidad en la abundancia relativa, estructura por tallas y proporción de sexos del dorado Coryphaena hippurus (Pisces: Coryphaenidae) en el Golfo de Tehuantepec, México

Variability in the relative abundance, size structure and sex ratio of the dolphinfish Coryphaena hippurus (Pisces: Coryphaenidae) in the Gulf of Tehuantepec, México. The dolphinfish (Coryphaena hippurus), is an oceanic epipelagic fish found worldwide in tropical and subtropical waters, with a high dispersal capability via large-scale migrations. This fast-swimming top-level predator is abundant in the Gulf of Tehuantepec, where it is caught incidentally by artisanal fisheries, and represents a target species for both recreational and commercial fisheries in Mexico, Ecuador, Peru and Central America. Nowadays, local fishery information on this species is scarce, thus our objective was to analyze the size structure by sex and the catch-per-unit-effort (CPUE) tendency of dolphinfish caught in the Gulf of Tehuantepec, from 2000 to 2007. For this, fishery catches information was obtained from the artisanal fleet, at six landing sites in the Gulf, and the sex ratio, fork length (FL) and the catch per unit effort (CPUE) were estimated. From all sampling sites, a total of 3 494 females, and 3 877 males were obtained, and dolphinfish size as fork length (FL) ranged from 20.5 to 152cm. Fish size ranged from 25.5 to 148cm furcal length (FL) in males, and 20.5 to 129cm FL in females. The sex ratio (males:females) was 1:1, except in April-May (1:1.5, p < 0.05) and November (1:0.5, p < 0.05). The sex ratio at different size classes showed a significant bias towards females at smaller sizes (< 75cm FL), whereas the males were predominant in larger size classes (> 100cm FL). The size structure was bimodal, with a variation in the size average; the modes were defined as the small group (FL = 50-55cm) and the large size group (FL = 100-110cm). The CPUE showed seasonal changes: values were high for the November-December period, and values were lower for July-August. The seasonal and inter annual variation in the abundance of dolphinfish is probably related to a pre-spawning migration in close relation to the rain-drought regime characteristic of the region, and the associated wind upwelling season of "Tehuanos" in the Gulf of Tehuantepec.

Reproductive Strategies of the Eastern OysterCrassostrea virginica(Gmelin 1791) in Tropical Lagoons of the Mexican Gulf of Mexico

The oyster fishery is 1 of the most important coastal fisheries in Mexico. Management is based on a minimum legal size of 80 mm and several seasonal bans that vary along the coast of the Gulf of Mexico. We describe the gonad development cycle of Crassostrea virginica (Gmelin 1791) along the Mexican coast of the Gulf of Mexico for 5 lagoons for the years 2000 and 2004, between latitudes 2141'16.75'' N and 1823'51.08'' N. Significant differences in duration and intensity were observed among reproductive stages associated with different environmental conditions. Gametogenesis and mature stages correlated positively with temperature and total chlorophyll, respectively. Spawning correlated negatively with salinity in both years. Maturity correlated positively with total chlorophyll levels. The reproductive stages varied from seasonal, a few months, to continuous throughout the year. Recovery, expressed as the number of organisms in postspawning and resting stages, was fast for populations that presented constant gametogenesis and spawning, with less than 50% of the population in postspawning and resting stages. Environmental fluctuations in total chlorophyll are the regulating factors for gametogenic activity, rather than latitudinal temperature variations. This makes monitoring environmental conditions in the lagoons or gonad development a necessity to predict reproduction and recruitment for proper management of the oyster resource.

Reproductive biology of Holothuria fuscocinerea (Echinodermata: Holothuroidea) from Oaxaca, Mexico

The sea cucumber Holothuria fuscocinerea is among the most common holothurian species widely distributed in the Tropical Eastern Pacific Region and is becoming a potentially important fishery in Mexico. Nevertheless, there are no studies about its reproductive biology. This study analyzed several reproductive traits of H. fuscocinerea based on monthly time-series samples taken from April 2008 to March 2009 at La Entrega Bay, Oaxaca, in the Mexican tropical Pacific. Sex ratio, gonad development stages (GDS), reproductive cycle, diameter and distribution of oocytes, and fecundity were determined. Reproductive indices (the gonadosomatic index (GSI) and maturity index (MI)) were calculated, and their relationship with some environmental factors (temperature, rainfall, salinity, and pH) was evaluated. H. fuscocinerea is a gonochoric holo - thuroid, and its annual ratio of males to females was not significantly different from 1:1. Four GDS (i.e. gametogenesis, mature, spawning, post-spawning) as well as one period of gonadal recovery, which is 'sexually undifferentiated', were established. Spawning occurred from June to October in females and from April to September in males. Post-spawning of females and males and recov- ery stages coincided from October to January. Mean fecundity was 2.9 ± 2.8 million oocytes per female, with ovaries exclusively comprised of vitellogenic oocytes from June to September. GSI and MI values showed similar variations in accordance with the reproductive cycle, and GSI showed a relationship with rainfall season. Seasonal rainfall may act as a cause of the seasonal reproductive pattern observed in H. fuscocinerea.

Subsidies in the jumbo squid fishery in the Gulf of California,Mexico

This paper investigates the effects of fuel subsidies and value added tax refunds on the operation of two types of firms associated with the jumbo squid ( Dosidicus gigas ) fishery in Mexico: (a) firms with ships that catch shrimp and squid in different periods of the year and (b) firms that deploy outboard-motor boats to catch squid year-round. The cost-benefit ratios of the policies are analyzed for 2008–2015, both with and without subsidy-related income. Additionally, the net cash surplus is calculated. The elimination of subsidies may affect jobs related to vessel operations in the squid fishery and may also encourage the voluntary retirement of shrimp ships. This effect is less evident in the case of the smaller boats. Strategies aimed at improving the landed squid prices are nonetheless suggested. ► Fishing subsidies are granted to increase firm profit margins. ► Subsidies effects vary according to the availability species. ► Subsidies for fishing firm type may be appropriate. ► Elimination of subsidies could increase retirement ofships.

The jellyfish fishery in Mexico

Jellyfish has been captured in Asia for 1700 years, and it has been considered a delicacy. Since the 70s important jellyfish fisheries have developed in several parts of the world, with catches increasing exponentially, reaching 500,000 tons per year in the mid-nineties. In Mexico, only the cannonball jellyfish Stomolophus meleagris is captured commercially. Most of the capture of this jellyfish species is obtained within the Gulf of California, specifically in the state of Sonora. The total reported capture in 2010 was 16,581 metric t and 14,220 in 2011. With these capture volumes jellyfish was ranked as the third most important fishing resource in the state of Sonora. The fishing season in Sonora is from April to May; a total of 4 or 5 weeks, and the catch per unit effort is around 3 tons by trip. Currently, there are nine jellyfish marketing companies, with about 20 processing plants distributed along the coast of Sonora, primarily in Guaymas, Kino Bay, and Puerto Penasco. Although the process is simple, the large amounts of jellyfish required and the need to optimize production costs make jellyfish processing an intense activity that employs hundreds of people during the fishing season, becoming an alternative employment for the people who depend on the fishing industry.

Mercury in the Gulf of Mexico: Sources to receptors

Gulf of Mexico (Gulf) fisheries account for 41% of the U.S. marine recreational fish catch and 16% of the nation's marine commercial fish landings. Mercury (Hg) concentrations are elevated in some fish species in the Gulf, including king mackerel, sharks, and tilefish. All five Gulf states have fish consumption advisories based on Hg. Per-capita fish consumption in the Gulf region is elevated compared to the U.S. national average, and recreational fishers in the region have a potential for greater MeHg exposure due to higher levels of fish consumption. Atmospheric wet Hg deposition is estimated to be higher in the Gulf region compared to most other areas in the U.S., but the largest source of Hg to the Gulf as a whole is the Atlantic Ocean (>90%) via large flows associated with the Loop Current. Redistribution of atmospheric, Atlantic and terrestrial Hg inputs to the Gulf occurs via large scale water circulation patterns, and further work is needed to refine estimates of the relative importance of these Hg sources in terms of contributing to fish Hg levels in different regions of the Gulf. Measurements are needed to better quantify external loads, in-situ concentrations, and fluxes of total Hg and methylmercury in the water column, sediments, and food web.

Status of Geoduck Clam Fisheries in Mexico

There are 2 species of geoduck fished commercially in northwest Mexico: Panopea generosa, along the Pacific coast of the Baja California peninsula, and Panopea Globosa, in the Gulf of California and in Bahía Magdalena. This study describes the status of the geoduck clam fishery in northwestern Mexico. Recent surveys suggest an ample distribution of beds along both coasts of Baja California and the coast of Sonora. Landings have increased from 49 mt in 2002 to 2,000 mt in 2011. The fishery has a current annual value of approximately US$30 million, and in Sonora, stock assessments estimate the potential yield to be around 1,800 mt. Fishers in Sonora have expressed an increasing interest to enter into the geoduck fishery, and a total of 1,173,898 pieces have been authorized for new extraction in 2012. We have conducted surveys in 24 beds from February 2009 to October 2011 to evaluate the resource. Given the long life cycles of geoduck, low recruitment and high fishing rates threaten the viability of this resource unless immediate management actions are taken.

Management Implications of the Biodiversity and Socio-Economic Impacts of Shrimp Trawler By-Catch in Bahía de Kino, Sonora, México

The shrimp fishery is the most economically important fishery in Mexico. The trawler-based portion of this fishery results in high rates of by-catch. This study quantifies and describes the biodiversity of by-catch associated with trawling in the Bahía de Kino region of Sonora, Mexico. Data were collected from 55 trawls, on six boats, over 14 nights, during November of 2003, 2004, 2006–2009. By-catch rates within trawl samples averaged 85.9% measured by weight. A total of 183 by-catch species were identified during the course of this study, including 97 species of bony fish from 43 families, 19 species of elasmobranchs from 12 families, 66 species of invertebrates from eight phyla, and one species of marine turtle; seven of the documented by-catch species are listed on the IUCN Red List, CITES, or the Mexican NOM-059-ECOL-2010; 35 species documented in the by-catch are also targeted by local artisanal fishers. Some of the species frequently captured as juveniles in the by-catch are economically important to small-scale fishers in the region, and are particularly sensitive to overexploitation due to their life histories. This study highlights the need for further research quantifying the impacts of high levels of by-catch upon small-scale fishing economies in the region and presents strong ecological and economic rationale for by-catch management within the shrimp fishery of the Gulf of California. Site-specific by-catch management plans should be piloted in the Bahía de Kino region to address the growing momentum in national and international fisheries policy regimes toward the reduction of by-catch in shrimp fisheries.

Effects of tag type on red snapper Lutjanus campechanus tag retention, growth and survival under hatchery conditions

Summary Management of red snapper stocks is one of the most controversial issues in the Gulf of Mexico fisheries. Fish tagging programs can help to address many management issues if an appropriate tag is selected. In the study three types of tags were tested to determine tag retention and effects on red snapper growth and survival. Hatchery-produced juveniles (43.7 ± 5.6 g) were either not tagged or given: internal anchor tags anchored in the abdominal cavity; passive integrated transponders (PIT) tags injected into the body cavity; or metal self-piercing fish tags clamped around the dentary bone. Fish were stocked at 25 m−3 in three replicate circular tanks/tag type, and fed a commercial feed for a 150 days period. Fish survival did not differ by treatment. Average weight gains after 150 days were similar. Tag retention differed by treatment (P = 0.0002), with 100% retention of PIT tags, 98.4 ± 2.8% retention of jaw tags, and 90.4 ± 1.6% retention of internal anchor tags. Loss of internal anchor tags occurred primarily within the first month. Inflammation was frequently observed at the internal anchor tag insertion site. Irritation and cell proliferation was sometimes observed in areas around the jaw tags.

Bioaccumulation of microcystins by fish associated with a persistent cyanobacterial bloom in Lago de Patzcuaro (Michoacan, Mexico)

Lago de Patzcuaro is a historically important freshwater fishery in Mexico. The lake is presently characterized by a persistent bloom of cyanobacteria, specifically dominated by recognized producers of toxic microcystins (MCYSTs). We evaluated MCYSTs in sestonic and dissolved fractions of the water column, as well as representative fish species (silversides, Chirostoma spp.; Goodea sp.; and carp, Cyprinus carpio) obtained from local markets and small commercial catches during the bloom. Samples were evaluated primarily by enzyme-linked immunosorbent assay (ELISA), and secondarily by protein phosphatase (PPase) inhibition assay and liquid chromatography-mass spectrometry (LC-MS). Sestonic MCYST concentration (0.02-0.36 µg/L) generally correlated inversely with distance from the bloom, supporting the bloom as the source of the toxin. Several MCYST variants, including MC-LR, -LA and -LY, as well as didemethyl variants, were identified by LC-MS/MS analysis. All three species of fish bioaccumulated MCYSTs in relevant tissues, and toxin content correlated with trophic level, with highest and lowest levels measured in phytoplanktivorous and zooplanktivorous representatives, respectively. Detection of MCYST in silversides and Goodea sp. is particularly relevant because both are consumed in their entirety, including viscera (e.g., liver) known to primarily accumulate MCYST. These results indicate that Lago de Patzcuaro is indeed characterized by a toxigenic bloom, and that commercially important fish species from the lake accumulate toxic MCYST in tissues relevant to human consumption. As such, this system may represent an ideal model of the trophic transfer of MCYSTs and its relevance to human and environmental health.

Spatial management of small-scale fisheries on the west coast of Baja California Sur, Mexico

To understand small-scale fisheries in Mexico, the spatial and temporal distribution of the landed catch of several species was analyzed, including abalone, clams, snails, octopus, squids, lobsters, shrimps, blue crabs, sharks, rays and finfish along the 349 km of the Gulf of Ulloa coast. Data reported by fishers from 1998 to 2009 on catch volume and value per group of species and per fishing locality, together with the number of landing events, were used to define fishing zones and the relative importance of each fishery. Finfish turned out the primary fishery in the region, but the other fisheries showed relevant spatial changes that should be considered when establishing management goals and fishing regulations according to resource availability, fleet efficiency, processing capacity, commercialization of fishing products and profit distribution.

Determining policy-efficient management strategies in fisheries using data envelopment analysis (DEA)

Abstract In this paper, the authors analyze a wide range of recreational management strategies for their impacts on red snapper yield, economic surplus and the fish stock. Simulating a wide range of policies, the authors find Data Envelopment Analysis (DEA) inspired policy efficiency frontiers that lead to finding those management strategies that offer the greatest level of economic surplus for any biological target, looking at both the east and west Gulf of Mexico fisheries. Red snapper has been declared overfished since 1988 and the 2005 SEDAR 7 stock assessment declared red snapper were overfished and undergoing overfishing. In November 2009, the update of the assessment declared that overfishing was no longer occurring but that the red snapper stocks needed to be rebuilt. In this analysis, it was found that red snapper are neither overfished or undergoing overfishing. The main difference between the present model and the SEDAR 7 model is that the latest model uses a higher mortality rate for juveniles and a density dependent model. The authors also suggest that the east and west should be managed as separate units.

Contextual factors influencing sustainable fisheries in Mexico

Abstract Sustainable fisheries take into consideration that managed fisheries ecosystems shift over time in response to evolving environmental as well as market and political factors. These contextual forces are especially valuable in understanding developing countries such as Mexico, where the unconsolidated fisheries administration faces productive marine ecosystems but unsustainable fisheries. To recognize the issues that have inhibited the consolidation of a regulatory system for sustainable fisheries, a contextual factor analysis was applied to the co-development of two current policies in the Mexican fishery regime: fisheries and environmental policies. Six historical phases have been identified in which there are few long periods of stability and frequent short periods of radical change that alternate between stable and adverse contextual situations. These short and contrasting contextual situations cause a kind of tug-of-war in Mexican fisheries policy-making. On the one hand, domestic economic, scientific, and technological forces seem to slowly lead toward the consolidation of sustainable fisheries; on the other hand, domestic policies drift from one position to another at other timing than the international fisheries and environmental policies. Although recent crises seem to highlight new periods of radical change in Mexico, they also provide an opportunity to adopt new structural plans to consolidate domestic forces as a basis for long-term strategies.

Responses of the fishing sector to transitional constraints: From reactive to proactive change, Yucatan fisheries in Mexico

Abstract Most fisheries management studies have concentrated on understanding resource dynamics and have paid less attention to understanding the dynamics of those who use the resources. This situation limits the knowledge about the fisheries system as a whole and specifically about the viability of management schemes. It is vital to understand how the actors within the fishing sector (fishing firm owners/managers, fishers, fisheries managers, and traders) may respond to changes in fishing resources trends, market dynamics, and fisheries policies before they are implemented. These issues are explored in this paper by applying a longitudinal analysis of the Yucatan Mexico's fishing industry. The analysis is presented within the framework of the theory of change and coping strategies. The study primarily involved interviews during 2008 with the main owners of companies in the fishing industry and with fisheries managers and other stakeholders. Time-series catch data on the main fishing resources are also reviewed to evaluate changes across three historical periods and describe how the actors have perceived and responded to those changes. Given conditions of uncertainty in resource availability, changes in market demand and changes in institutional arrangements, the viability of traditional business and resource management practices are discussed. The analysis presents different kind of triggers that have modified the conditions of the fishing sector and had had impacts on the socio-economic–ecological system in which fisheries are embedded. The need for adaptive strategies in the whole chain of the fisheries business and resource management is stressed, given the current changes and conditions of fisheries. The discussion states a series of actions that could improve the relationships between business practices and fisheries management.

The Legacy of Oil Spills

The Legacy of Oil Spills

Red snapper management in the Gulf of Mexico: science- or faith-based?

The most controversial fishery in U.S. waters of the Gulf of Mexico (Gulf) is for northern red snapper Lutjanus campechanus, which collapsed in the late 1980s when stock biomass became too low to be fished commercially in the eastern Gulf. Red snapper management began in 1989; the stock is now showing signs of recovery. The Gulf of Mexico Fishery Management Council has been slow to sufficiently reduce catches of the directed fisheries to rebuild the stock in a timely fashion, although compliance with the Magnuson-Stevens Reauthorization Act of 2006 (MSRA) required substantial cuts in the harvest of red snapper beginning in 2007. In our opinion, this could have been avoided if conservative management practices had been adopted earlier. We believe that ‘faith-based fisheries’ arguments have been used to defer effective management of red snapper in the Gulf, which in turn has strained the relationship between science, management, and stakeholders there. We provide a simple empirical argument and alternate interpretations of a recently published perspective on the historical fishery of red snapper in the Gulf to conclude that the preponderance of evidence used in the agency stock assessment process, and the simple arguments made here, do not support the perspective that the red snapper stock has increased in size sufficiently to defer compliance with the MSRA.

Reanalyses of Gulf of Mexico fisheries data: Landings can be misleading in assessments of fisheries and fisheries ecosystems

We used two high profile articles as cases to demonstrate that use of fishery landings data can lead to faulty interpretations about the condition of fishery ecosystems. One case uses the mean trophic level index and its changes, and the other uses estimates of fishery collapses. In earlier analyses by other authors, marine ecosystems in the Gulf of Mexico (GOM) and U.S. Atlantic Ocean south of Chesapeake Bay were deemed to be severely overfished and the food webs badly deteriorated using these criteria. In our reanalyses, the low mean trophic level index for the GOM actually resulted from large catches of two groups of low trophic level species, menhaden and shrimp, and the mean trophic level was slowly increasing rather than decreasing. Commercial targeting and high landings of shrimps and menhaden, especially in the GOM, drove the index as previously calculated. Reanalyses of fishery collapses incorporating criteria that included targeting, variability in fishing effort, and market forces discovered many false cases of collapse based simply upon a decline of catches to 10% of previous maximum levels. Consequently, we suggest that the low mean trophic level index calculated in the earlier article for the GOM did not reflect the overall condition of the fishery ecosystem, and that the 10% rule for collapse should not be interpreted out of context in the GOM or elsewhere. In both cases, problems lay in the assumption that commercial landings data alone adequately reflect the fish populations and communities.

Biological and Ecological Mechanisms Supporting Marine Self-Governance: the Seri Callo de Hacha Fishery in Mexico

Basurto, X. 2008. Biological and ecological mechanisms supporting marine self-governance: the Seri callo de hacha fishery in Mexico. Ecology and Society 13(2): 20. https://doi.org/10.5751/ES-02587-130220