Seasonal Ban Research Articles

Reproductive biology of green tiger shrimp Penaeus semisulcatus De Haan, 1844 in Palk Bay, southeast coast of India

Penaeus semisulcatus forms a single-species fishery of significant importance along Palk Bay’s southeast coast of India. The reproductive biology of the species was studied from the region as parameters like ovary development, maturity stages, and the spawning season are necessary for better management of the resources. The male testis of P. semisulcatus has eight testicular lobes with oval-shaped ampoules. Chromatin oocytes in immature females, cortical oocytes in mature females, and Atreatic oocytes in mature females were observed. The dark green (or greenish brown) ovary with elongated cortical bodies in the periphery of the ova is fully mature. The spawning season is most active in the post-monsoon and monsoon, with a minor peak in the pre-monsoon. The Lm50 determined was extremely low when compared to other studies conducted on the species, which is attributed to fishing pressure. Males mature earlier than females, and they do not have specific seasons or cyclic changes. The female-to-male ratio was not equal, and females were always found in greater numbers. Beyond 3 Nautical Miles (NM), the entire Palk Bay is designated as a spawning ground, while up to 3 NM, is designated as a nursery ground. These species can be harvested sustainably by imposing a seasonal ban on shrimp fishing during the peak breeding season, regardless of gear.

Achieving international biodiversity targets: Learning from local norms, values and actions regarding migratory waterfowl management in Kazakhstan.

Migratory species are protected under international legislation; their seasonal movements across international borders may therefore present opportunities for understanding how global conservation policies translate to local‐level actions across different socio‐ecological contexts. Moreover, local‐level management of migratory species can reveal how culture and governance affects progress towards achieving global targets. Here, we investigate potential misalignment in the two‐way relationship between global‐level conservation policies (i.e. hunting bans and quotas) and local‐level norms, values and actions (i.e. legal and illegal hunting) in the context of waterfowl hunting in northern Kazakhstan as a case‐study.Northern Kazakhstan is globally important for waterfowl and a key staging area for arctic‐breeding species. Hunting is managed through licences, quotas and seasonal bans under UN‐AEWA intergovernmental agreements. To better understand the local socio‐ecological context of waterfowl hunting, we take a mixed‐methods approach using socio‐ecological surveys, informal discussions and population modelling of a focal migratory goose species to: (a) investigate motivations for hunting in relation to socio‐economic factors; (b) assess knowledge of species' protection status; and (c) predict the population size of Lesser White‐fronted Geese (LWfG; Anser erythropus; IUCN Vulnerable) under different scenarios of survival rates and hunting offtake, to understand how goose population demographics interact with the local socio‐ecological context.Model results showed no evidence that waterfowl hunting is motivated by financial gain; social and cultural importance were stronger factors. The majority of hunters are knowledgeable about species' protection status; however, 11% did not know LWfG are protected, highlighting a key area for increased stakeholder engagement.Simulations of LWfG population growth over a 20‐year period showed LWfG are highly vulnerable to hunting pressure even when survival rates are high. This potential impact of hunting highlights the need for effective regulation along the entire flyway; our survey results show that hunters were generally compliant with newly introduced hunting regulations, showing that effective regulation is possible on a local level. Synthesis and applications. Here, we investigate how global conservation policy and local norms interact to affect the management of a threatened migratory species, which is particularly important for the protection and sustainable management of wildlife that crosses international borders where local contexts may differ. Our study highlights that to be effective and sustainable in the long‐term, global conservation policies must fully integrate local socio‐economic, cultural, governance and environmental contexts, to ensure interventions are equitable across entire species' ranges. This approach is relevant and adaptable for different contexts involving the conservation of wide‐ranging and migratory species, including the 255 migratory waterfowl covered by UN‐AEWA (United Nations Agreement on the Conservation of African‐Eurasian Migratory Waterbirds).

Sea cucumber fishery in Turkey: Management regulations and their efficiency

Sea cucumbers have a commercial importance worldwide but are facing over-exploitation and population collapse. The aim of this study was to document the fishing condition and illegal fishing on sea cucumber fishery in the Mediterranean coast of Turkey based on fishery reports, to ascertain the implementation and efficiency of management regulations. Sea cucumber fishing began in 1996 and expanded, now having 220 vessels extracting up to 1292 tonnes in 2019. Between 2015 and 2020, 80 tonnes of sea cucumbers have been seized and thrown into the sea in 541 infringements. Illegal activities differed in the geographical area covered and concentrated on Izmir shores in 2018–2019. Fishery regulations and fines implemented until 2020 were not effective as deterrent. Since 2007, sea cucumber fishery has had legal regulations including seasonal bans, licensing issues, market chain reporting, fishing vessels limits, and rotational harvesting. New regulations, based on quotas and fine amount increase, were effective in January 2020 due to illegal fishing. Consequently, there was a decrease in the number of infringements.

Population genetic structure of the oceanic whitetip shark, Carcharhinus longimanus, along the Indian coast

Sharks are undergoing population declines worldwide and it is imperative to devise conservation and management strategies to prevent their extinction. Oceanic whitetip sharks are large pelagic sharks distributed circumglobally and recent IUCN assessments classified them as “critically endangered.” Considering their vulnerability, we investigated the intraspecific diversity and genetic stock structure of oceanic whitetip shark, Carcharhinus longimanus, along the Indian coast using mitochondrial control region sequences so that viable management guidelines can be formulated in the Indian Ocean region. Population genetic analyses revealed a lack of significant genetic differentiation along the Indian coast indicating substantial gene flow and connectivity among populations. Comparisons of data of the present study with that of Atlantic Ocean regions indicated significant connectivity and gene flow between Indian and East Atlantic regions and a lack of connectivity between Indian and West Atlantic Ocean regions. Oceanic whitetip sharks have substantial capacity for oceanic migration resulting in the mixing of gene pools. Despite these capabilities, overfishing is one of the major drivers of population decline worldwide, resulting in severe fragmentation of populations. Based on the results of the present study, this species can be managed as a single stock along the Indian coast. Further co-management measures along with countries bordering East Atlantic coast can also be devised. Management should consider a complete or seasonal ban of the fishery in addition to restrictions in gear types.

Shellfish contamination with marine biotoxins in Portugal and spring tides: a dangerous health coincidence.

Bivalve molluscs can acquire marine biotoxins by filter-feeding upon certain toxin-producing microalgae. The two most common syndromes observed in temperate coastal waters have been diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP). While DSP is a non-fatal gastrointestinal syndrome, PSP is a neurological syndrome which can lead to death by respiratory paralysis in high intoxication scenarios. In Portugal, the presence of both DSP and PSP toxins leads to recurrent seasonal bans of bivalve harvesting. On a few occasions, the bans were not placed in time, not properly disseminated to the public or were disregarded by recreational harvesters. Several cases of poisonings have been studied in collaboration between health authorities and the laboratory in charge of the biotoxin monitoring programme. Some of the outbreaks have even called the attention of the local media. In several of these recorded cases, a common trait has emerged throughout the years: bivalve harvest had often been done during very low tides attributed to either new or full moons. These tides expose intertidal bivalves more widely, increase harvesting time, and allow picking of larger-sized specimens. In some occasions, the consumers were extremely unfortunate because a noxious coincidence had occurred: larger-sized specimens were available but had attained the highest toxin content of the toxic season. This review alerts that despite costly monitoring programmes have been perfected through the years, human poisonings still take place due to the rapid increase in toxin levels and/or disrespect of harvest bans.

Aspects of Reproductive Ecology of Chrysichthys Auratus in the Volta Lake, Ghana

The study was conducted in 2018, on the Chrysichthys auratus in the Volta Lake, due to its socio-economic importance to the many and varied dependent fishermen, fish processors and fish traders. The objective was to determine the reproductive strategy to facilitate sustainable management of the fish stocks. A total of 452 fish samples collected on monthly basis were measured, weighed and dissected for determination of, sexual maturity, sex ratio, gonadosomatic index GSI, hepasomatic index HSI, condition factor k, visceral fat index VFI, and monthly stomach fullness in relation to sexual maturity. According to the length at first maturity determined, 89% of the female fish caught, fell below that critical length, suggesting growth overfishing, attributed to size and sex selective tendencies of bamboo pipe fishing. During gonad development, the correlation of the GSI to the HSI and the VFI was inverse and insignificant but in the post gonad development phase it switched to a positive and insignificant relationship. The point of switch, in September, was synonymous with spawning and indicative of the spawning period. It was concluded that the reproductive strategy was to time the spawning process, in September, to coincide with the upwelling phenomenon (June – September), associated with fish food abundance, thereby enhancing the survival of the offspring. A seasonal ban on fishing and a total ban on bamboo pipe fishing were recommended.

Unintended consequences of a seasonal ban on fishing effort in Tamil Nadu & Puducherry, India

Fisheries regulations can have a host of implications for both fishers and the fishery they aim to protect. Oftentimes there are unanticipated adaptations employed by resource users in the face of restrictions. Unintended consequences of fisheries regulations are examined through the case of an annual 45-day closed fishing season in India. Using a longitudinal study design over the course of three seasons: before, during and after the 2015 seasonal fishing ban, seasonal activities calendars and semi-structured interviews were employed to randomly selected participants (n = 171) within two fishing villages in Tamil Nadu and Puducherry, India. Data suggests that some fishers shift their fishing effort to unrestricted gears during the ban and that post-ban race for fish is exemplified by all gear types, though an illegal, unregulated gear type, locally termed surukku valai exhibits the largest increase in effort. Lack of fishing-related employment options during the ban period leads to high levels of unemployment and food security concerns. Using data on average landings for each gear type, post-ban fish catch is estimated and impacts to local fish populations are projected.

Valuing Public Preferences for Ludong (Cestraeus plicatilis Valenciennes 1836) Conservation Program in Cagayan River Systems, Philippines

Ludong (Cestraeus plicatilis Valenciennes 1836) has been declared as an endangered species by the Bureau of Fisheries and Aquatic Resources (BFAR) in the Cagayan River Systems. Thus, BFAR is planning to ban ludong fishing for five years that will be complemented by changes in the current conservation program. This study determined and valued the program features preferred by 282 respondents from eight major ludong fishing and trading sites along the Cagayan River Systems in provinces of Cagayan and Isabela for the BFAR’s 5-year proposed revised ludong conservation program using a choice experiment approach. The heterogeneity of the respondent’s preferences for these program features was also determined. The respondents had the highest mean willingness to pay (PhP 534.07 per year) for a conservation program that has the lowest negative income impacts to them given their heavy reliance to fishing as income and food source. This program bans only ludong fishing gears from October to December 15, provides income benefits to them during the 2.5 months seasonal ban for ludong and provides information and education about ludong via a medium that is easily and widely accessible to them. The differences of their willingness to pay for these program features are low.

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 cycle of the traditionally exploited sea cucumber Holothuria tubulosa (Holothuroidea: Aspidochirotida) in Pagasitikos Gulf, western Aegean Sea, Greece

The reproductive cycle of the traditionally exploited sea cucumber Holothuria tubulosa was investigated in the Pagasitikos Gulf (39°18'457\"N, 23°05'869\"E) from June 2007 to July 2008. The study examined the microscopic characteristics of the gonads and was based on maturity index (MI) and oocytes' size-frequency distribution. The reproductive cycle was found to be synchronous between sexes, following an annual pattern. The minimum MI values were recorded in December and January, marking the onset of the reproductive cycle. During the spring, MI increased due to gamete development and proliferation. Mature specimens were prominent in summer while spawning occurred between July and September. The maximum MI values were recorded in mid-autumn, when most specimens were at the postspawning stage. The oocytes' size-frequency distribution showed analogous seasonal variability. The present findings are crucial for establishing an efficient management strategy for this commercial and ecosystem-engineering species, since its exploitation in Greek waters has not been under official control for more than a century. The authors propose a seasonal ban on the exploitation of the species from July to September and a minimum individual drained weight limit of 250 g.

NEWS OVERVIEW: Researchers develop alternatives to methyl bromide fumigation

finding alternatives to News overview Researchers develop alternatives to methyl bromide fumigation T Brad Hanson ime is running out for California grow- ers who still use methyl bromide. This soil fumigant is just short of a miracle for pest management — a single treatment before plant- ing controls nematodes, diseases and weeds. But methyl bromide is also a health and environmental hazard, and is being phased out under an inter- national ban. To help growers make the inevitable transition, UC and U.S. Department of Agriculture (USDA) researchers just spent 5 years testing methyl bromide alternatives for key western crops with a $5 million grant from the USDA. The program’s research is presented in the current and the coming October–December issue of California Agriculture. “One goal of the program was to identify methyl bromide alternatives that were immediately use- ful and economically feasible,” says Greg Browne, a USDA plant pathologist at UC Davis who was project coordinator for the research program. “Another was to foster development of non-fumi- gant strategies for managing soilborne pests.” Growers have used methyl bromide since the 1960s to effectively sterilize fields before planting. But this toxic gas is so volatile that more than half of the amount injected into soil can eventually end up in the air. When methyl bromide rises high in the atmosphere, it contributes to thinning of the ozone layer (the layer that shields us from ultravio- let radiation). In 2005, developed countries banned methyl bromide under the Montreal Protocol, an international treaty signed in 1987 to protect the stratospheric ozone layer. Even so, the treaty still allows limited use of methyl bromide in certain cases today. These in- clude critical use exemptions for strawberries, almonds and other crops that lack alternatives that are both effective and affordable, as well as quar- antine and preshipment exemptions for rootstock, Alternative fumigants such as 1,3-D may be the best option in the short term for nursery stock, which must be completely nematode-free to meet California’s phytosanitary certification requirements. bulbs and other nursery crops that could spread pests to new places. This authorized use shrinks each year, however, and will soon end. In the United States, recent methyl bromide use is down sharply from the 1991 baseline of 28,000 tons. The nationwide exemption for 2013 is 2.2% of baseline, or about 620 tons, and in 2014 this will drop further to 1.7% of baseline, or about 480 tons. The exemp- tion for 2015, if any, is unknown. For comparison, California alone used 3,550 tons of methyl bromide in 2004, the year before it was banned. Other restrictions on methyl bromide use in- clude seasonal bans to cut air pollution, and the requirement of buffer zones to protect people’s health. While methyl bromide depletes the protec- tive ozone in the stratosphere, it adds to ground- level ozone or smog. Thus, its use is prohibited during the warm months in parts of the state with poor air quality, including the San Joaquin Valley and Ventura County. Moreover, methyl bromide– free buffers are required around sites that are hard to evacuate, such as schools, hospitals and jails, because high concentrations of this fumigant can cause lung, eye and skin damage as well as respira- tory and central nervous system failure. Finding alternatives Most of the dwindling U.S. methyl bromide allotment goes to California and Florida, so the USDA Agricultural Research Service launched twin research initiatives to help find alternatives for growers in these regions. “The programs focused on the most important needs in the west and south- east,” says Browne. “The crop mixes were based on the views of growers and other stakeholders.” The western program, called the Pacific-Area Wide Integrated Methyl Bromide Alternatives Program, includes production crops such as grapes, strawber- ries and tree nuts as well as nursery crops such as cut flowers, forest trees and sweet potatoes. The South Atlantic Area Extension Program for Methyl Bromide Alternatives, the southeast program, in- cludes crops such as strawberries, tomatoes, cucum- bers and peppers. Finding alternatives is a challenge because methyl bromide sterilizes soil so well. “Methyl bro- mide is a one-shot control. It does so much that it’s hard to find a true replacement,” says Brad Hanson, a UC Cooperative Extension (UCCE) weed special- ist at UC Davis. In addition, the best alternative varies, depending partly on the primary benefit a particular crop gets from methyl bromide. For ex- ample, the biggest problems for production crops may be diseases or weeds. But the biggest problem http://californiaagriculture.ucanr.edu • JULY–SEPTEMBER 2013

Fishing pattern and management scenarios of Epinephelus gabriellae (Randall and Heemstra, 1991) fisheries in the Arabian Sea, Oman

Summary Management of fish resources in the Western Indian Ocean is complicated due to the lack of data on the basic biology and landing statistics for exploited fish species. In this paper, a database including biological parameters, length frequency distributions and catches of Epinephelus gabriellae in Oman according to fleet components has been established to develop a management plan for its sustainable exploitation. Length cohort analyses and yield per recruit were examined by simulating changes in fishing effort in length at first capture and by introducing a seasonal ban for trawlers. The results showed a high sensitivity to the applied value of natural mortality (M). (i) With M = 0.40, a healthy status of the stock is observed; however, with M values of 0.20 and 0.15 the stock appears slightly overexploited, and actual F exceeds 10 and 30% of the F01 level, respectively. (ii) A moderate increase of length at first capture would not significantly affect the long-term yield or stock spawning biomass; however, a substantial length increase would in the long-term lead to a decrease in yields for the artisanal fleet using traps. (iii) A seasonal ban regulation for trawlers would not have a significant effect on the sustainable yield, but if the fishing effort were to increase considerably, a significant long-term gain in yield would be obtained with a closed season from April-September.

Fuel use and greenhouse gas emission implications of fisheries management: the case of the new england atlantic herring fishery

Commercial fisheries are heavily dependent upon the combustion of fossil fuels and as such contribute to increased atmospheric concentrations of greenhouse gases and the concomitant impact on the world's climate. The fuel use and greenhouse gas intensity of a fishery is a function of several variables. One that has not been previously investigated is the role of fisheries management. Using historical gear-specific fuel use and landings data, we employ scenarios to examine the potential impact that recent changes in the management of the New England fishery for Atlantic herring ( Clupea harengus ) may have on fishery-related fuel use and greenhouse gas emissions. Specifically, we consider the direct effect of the seasonal ban of midwater trawling in favor of purse seine and fixed gears within Atlantic herring fishing Area 1A. We also evaluate the indirect effect of reductions to the Area 1A total allowable catch of Atlantic herring on the regional supply of bait and the resulting potential need to import bait herring from Canada. Our results indicate that because of the five-fold lower fuel intensity of purse seining, relative to midwater trawling (21 L/ton versus 108-118 L/ton), the seasonal ban on midwater trawling has the potential to markedly reduce overall fuel use and greenhouse gas emissions associated with the herring fishery. These results indicate that management decisions can strongly influence energy demands and resulting greenhouse gas emissions of fisheries. We urge those involved with fisheries management to take this into account when developing policy and management measures.