Spawning Patterns Research Articles

Spawning of tiger grouper Epinephelus fuscoguttatus and squaretail coralgrouper Plectropomus areolatus in sea cages and onshore tanks in Andaman and Nicobar Islands, India

The broodstock of two grouper species, tiger grouper Epinephelus fuscoguttatus and squaretail coralgrouper Plectropomus areolatus, were maintained in sea cages near Rutland Island, Andaman and Nicobar Islands, India, and their spawning performance was monitored from June 2007 to December 2010. E. fuscoguttatus generally spawned monthly in association with the new moon phase, for 8–9months each year. Each year, they underwent a 3- to 4-month refractory period between February and June then recommenced spawning in May–July. P. areolatus showed a different spawning pattern to E. fuscoguttatus, spawning for less than 6months each year, also in association with the new moon, and demonstrating much longer refractory periods (up to 15months) than E. fuscoguttatus. Analysis of temperature data from the sea cage site showed that water temperature was significantly lower during spawning events than during comparable non-spawning periods. We postulate that one factor inhibiting spawning is higher water temperatures exceeding the upper thermal inhibitory limit for both grouper species during the hotter months of the year. Selected broodstock fish of both species were also maintained in onshore tanks fitted with recirculating filtration systems, but the spawning performance of both grouper species in the onshore tanks was inferior to broodstock held in the sea cages. E. fuscoguttatus maintained in onshore tanks spawned during only 5months of the 42-month study period, whereas E. fuscoguttatus held in the sea cages spawned during 29months over the same time frame. P. areolatus held in onshore tanks over the same period did not spawn, whereas P. areolatus held in sea cages spawned during 16months out of the 42-month study period.

Spatial Consistency of Chinook Salmon Redd Distribution within and among Years in the Cowlitz River, Washington

AbstractWe investigated the spawning patterns of Chinook Salmon Oncorhynchus tshawytscha on the lower Cowlitz River, Washington, using a unique set of fine‐ and coarse‐scale temporal and spatial data collected during biweekly aerial surveys conducted in 1991–2009 (500 m to 28 km resolution) and 2008–2009 (100–500 m resolution). Redd locations were mapped from a helicopter during 2008 and 2009 with a hand‐held GPS synchronized with in‐flight audio recordings. We examined spatial patterns of Chinook Salmon redd reoccupation among and within years in relation to segment‐scale geomorphic features. Chinook Salmon spawned in the same sections each year with little variation among years. On a coarse scale, 5 years (1993, 1998, 2000, 2002, and 2009) were compared for reoccupation. Redd locations were highly correlated among years. Comparisons on a fine scale (500 m) between 2008 and 2009 also revealed a high degree of consistency among redd locations. On a finer temporal scale, we observed that Chinook Salmon spawned in the same sections during the first and last week. Redds were clustered in both 2008 and 2009. Regression analysis with a generalized linear model at the 500‐m scale indicated that river kilometer and channel bifurcation were positively associated with redd density, whereas sinuosity was negatively associated with redd density. Collecting data on specific redd locations with a GPS during aerial surveys was logistically feasible and cost effective and greatly enhanced the spatial precision of Chinook Salmon spawning surveys.Received August 10, 2012; accepted February 14, 2013

Reproductive biology of the characid dourado Salminus franciscanus from the São Francisco River, Brasil

The neotropical characid Salminus franciscanus is an economically valuable migratory fish whose populations have been drastically reduced in recent decades due to industrial and economic development in Brasil. To study its reproduction, a total of 283 adult specimens were captured in the Upper São Francisco River, downstream from the Três Marias dam, Minas Gerais, south-eastern Brasil, from August 2009 to July 2010. The gonadal maturity stages were determined from histological features of the gonads and gonadosomatic index (GSI). Gametogenesis was assessed by light and electron microscopy. For analysis of the oocyte's surface and fecundity, mature females were subjected to hormonal induction and oocyte stripping. Fish in resting (Stage 1) were common in all samplings, ripening/ripe and spawning (Stages 2 and 3) were predominant in October–November and December–January and post-spawning (Stage 4) occurred from December–January extending until April–May. The GSI followed the morphological changes of gonadal maturation, with a peak in October–November, when maximum GSI (7.08 in females and 3.46 in males) was achieved. From scanning electron microscopy, stripped oocytes showed a funnel-shaped micropyle and a simple oocyte surface arrangement, which is typical for non-adhesive eggs. Fecundity ranged from 160 to 440×103 oocytes per female and 129 to 175×103oocytes/kg. The results of this study indicate that S. franciscanus reproduces in the Upper São Francisco River from October to January, exhibiting a total spawning pattern, non-adhesive eggs and high fecundity, providing support for aquaculture and conservation biology of this important neotropical characid fish.

Reproductive output traits of the simultaneous hermaphrodite <I>Serranus scriba</I> in the western Mediterranean

We studied multiple individual parameters that affect the reproductive output in the painted comber Serranus scriba , a simultaneous hermaphroditic fish that is widely exploited by recreational fishing in temperate marine coastal regions. Batch fecundity was significantly affected by maternal size, but was not related to maternal age or condition. However, egg quality as estimated by egg dry weight was significantly influenced by the interaction effect of maternal size and age. An empirical assessment demonstrated the existence of a diel spawning pattern based on a daily release of a partial fraction of eggs related to sunset time. Buoyancy varied during the incubation period, but it consistently resulted in positive buoyancy that situated the eggs near the top of the water column. This study represents the first estimation of reproductive output of the simultaneous hermaphrodites S. scriba and also provides a comprehensive study about the potential maternal factors that affect egg production. These results are a crucial step towards ongoing efforts to improve the stock assessment of this species.

Reproduction of the invasive bluespotted cornetfish Fistularia commersonii (Teleostei, Fistulariidae) in the Mediterranean Sea

We investigated the reproduction of the bluespotted cornetfish Fistularia commersonii, one of the most successful invaders of the Mediterranean Sea and Europe. The results highlighted a multiple spawning pattern with asynchronous oocyte development and an unrestricted testicular organization with cystic spermatogenesis. Eight maturity stages in females and four in males were described. The reproductive season lasted at least six months, from May to October, with a peak in August, but gravid specimens were observed up to December. The gonadosomatic index and condition factors were significantly correlated with water temperature. Spawning started at an average water temperature of 22°C. The species is reproductively adapted to the conditions occurring in the Mediterranean Sea and it is suggested that warming conditions could facilitate its success along the Northern and Western sectors of the basin.

Study on Physico-Chemical Parameters in Different Mangrove Regions, Southeast Coast of India

A study was undertaken to determine the physico-chemical parameters of water in different mangrove regions of Indian coast. Flora and faunas are living in that regions and it can provide wild life places for living and foraging. Physicochemical parameters are influence the species diversity, pattern of diversity, spawning, breeding and metabolic activities. The temperature, pH, salinity, dissolved oxygen and nutrients are the major master factors of coastal water ecosystem. These parameters are occurring optimum level for the survival of species and poor water quality can influence the species activities and patterns of behavior. However, the base line physico- chemical data is toward the further study of ecological and conservation of economically and they are living species diversity patterns.

The use of otolith microchemistry to investigate spawning patterns of European anchovy: A case study in the eastern Ligurian Sea (NW Mediterranean)

Spawning patterns of European anchovy were investigated in the eastern Ligurian Sea (NW Mediterranean) by using otolith microchemistry. Otolith cores of 1-year-old anchovies showed a homogeneous chemical composition, while those of 2 years old anchovies separated into five different groups. This suggests the occurrence of single vs. multiple spawning areas related to the two annual cohorts. Patterns of core microchemistry of 2 years old anchovies support the hypothesis of different spawning areas, possibly characterised by different salinity regimes, in the eastern Ligurian Sea (e.g. typical marine habitats like shelf edges vs. lower salinity locations like river mouths). Results suggest that: (1) stocks of European anchovy could depend on different spawning areas characterised by different environmental conditions; (2) patterns may change from year to year, and this could affect the annual risk of stock fluctuations or collapse; and (3) the use of otolith microchemistry is a promising approach for investigating spawning patterns of European anchovy.

On gonadic maturation and reproductive strategy in deep-sea benthic octopus Graneledone macrotyla

The new information reported in this paper is based on five maturing and mature females of the large-tuberculate octopus Graneledone macrotyla. These specimens were caught in bottom trawl surveys ATLANTIS 2009 (February 24 to April 1, 2009) and ATLANTIS 2010 (March 9 to April 5, 2010) carried out off the Argentinean Economic Exclusive Zone. Capture depth ranged from 475 to 921 m and sea bottom temperature between 2.8 and 3.1 °C. Development of the complex ovary, oviducts, and oviducal glands during gonadic maturation is described. The absence of spermathecae in the oviducal glands and the presence of fertilized eggs inside the ovary suggested that fertilization took place within the ovary. Histological techniques showed the presence of four types of oocytes. Maturing oocyte size–frequency distribution was polymodal. Fluorescence reaction showed that atresia occurred in both early and later oocyte maturation stages. Atresia affected 48–55 % of the initial number of oocytes. The maximum observed potential fecundity was estimated at 250–300 eggs. G. macrotyla showed a group-synchronous ovulation pattern, regulative atresia, and a batching spawning pattern with a few egg batches spawned intermittently over an extended period of spawning.

Kajian Aspek Reproduksi Ikan Lais Ompok hypophthalmus di Sungai Kampar, Kecamatan Langgam, Kabupaten Pelalawan, Provinsi Riau

Lais fish of Ompok hypophthalmus is one of high economic fish in Kampar river. It should be protected fromdecreasing of it population estimated due to decreasing of habitat quality and increasing of exploitation. Theobjectives of the research are to study reproduction biology of lais fish as the basic data for conservation. Thisresearch was conducted from January 2007 to January 2008. The results of O. hypophthalmus reproductionaspect show that the smallest female of maturity is 22,9 cm and male is 22,6 cm; the spawning season onSeptember to November; O. hypophthalmus is more appropriate spawning location to oxbow lake that closerelation with tributary; the spawning pattern indicated total spawner fish; the fecundity ranges from 3111 to 11164eggs and the egg diameter ranges 0,41-1,13 mm.

Seasonal and Tidally Driven Reproductive Patterns in the Saltmarsh Topminnow, Fundulus jenkinsi

Fundulus jenkinsi is recognized federally and within a number of northern Gulf of Mexico states as a Species of Concern. Little is known about its life history, but a detailed reproductive histology study of F. jenkinsi can provide the foundation needed to quantify reproductive parameters in this rare species in need of conservation. Monthly gonadosomatic index (GSI) of male and female F. jenkinsi indicated a spawning season from April through August. However, ovarian histological analysis suggested March through August was a more accurate spawning season. The multiple oocyte stages within F. jenkinsi in the spawning capable reproductive phase indicates batch spawning, similar to other members of its family. Many estuarine members of the family Fundulidae exhibit a semilunar spawning pattern, yet the oocyte composition of ovaries of F. jenkinsi suggested spawns occur multiple days around the time of spring tides both within a population and on the individual level. Spawning did not occur on neap tides, and no late secondary growth vitellogenic oocytes (SGl) were found in the majority of females captured during neap tide. The lack of SGl oocytes in females during the spawning season suggests the necessity for establishing a new sub-phase within the spawning capable phase, termed the redeveloping sub-phase. This new sub-phase is applicable to other batch spawning species with group synchronous oocyte development. This work contributes to a better understanding of the importance of intertidal saltmarsh habitat to F. jenkinsi, as spawning intensity appears to increase with tidal height and marsh inundation.

Spawning coordination of mates in a shell brooding cichlid.

Aim. External fertilisation requires synchronisation of gamete release between the two sexes. Adequate synchronisation is essential in aquatic media because sperm is very short-lived in water. In the cichlid Lamprologus callipterus, fertilisation of the eggs takes place inside an empty snail shell, where females stay inside the shell and males have to ejaculate into the shell opening. This spawning pattern makes the coordination of gamete release difficult. Methods. This study examined the synchronisation of males and females during egg laying. Results. The results showed that the male initiates each spawning sequence and that sperm release and egg laying are very well synchronised. 68% of all sperm releases occurred at exactly the same time when the female laid an egg, and 99% of ejaculations occurred within ±5 seconds from egg deposition. On average 95 eggs are laid one by one with intervals of several minutes between subsequent eggs, leading to a total spawning duration in excess of six hours. Conclusions. We discuss this exceptional spawning pattern and how it might reflect a conflict between the sexes, with males attempting to induce egg laying and females extending the egg laying period to raise the chance for parasitic males to participate in spawning.

Significant reduction of the Loop Current in the 21st century and its impact on the Gulf of Mexico

This study examines the potential impact of future anthropogenic global warming on the Gulf of Mexico (GoM) by using a downscaled high‐resolution ocean model constrained with the surface forcing fields and initial and boundary conditions obtained from the IPCC‐AR4 model simulations under A1B scenario. The simulated volume transport by the Loop Current (LC) is reduced considerably by 20–25% during the 21st century, consistent with a similar rate of reduction in the Atlantic Meridional Overturning Circulation. The effect of the LC in the present climate is to warm the GoM, therefore the reduced LC and the associated weakening of the warm LC eddy have a cooling impact in the GoM, particularly in the northern basin. Due to this cooling influence, the northern GoM is characterized as the region of minimal warming. Low‐resolution models, such as the IPCC‐AR4 models, underestimate the reduction of the LC and its cooling effect, thus fail to simulate the reduced warming feature in the northern GoM. The potential implications of the reduced warming in the northern GoM on pelagic fish species and their spawning patterns are also discussed.

Tradeoffs between homing and habitat quality for spawning site selection by hatchery-origin Chinook salmon

Spawning site selection by female salmon is based on complex and poorly understood tradeoffs between the homing instinct and the availability of appropriate habitat for successful reproduction. Previous studies have shown that hatchery-origin Chinook salmon (Oncorhynchus tshawytscha) released from different acclimation sites return with varying degrees of fidelity to these areas. To investigate the possibility that homing fidelity is associated with aquatic habitat conditions, we quantified physical habitat throughout 165 km in the upper Yakima River basin (Washington, USA) and mapped redd and carcass locations from 2004 to 2008. Principal components analysis identified differences in substrate, cover, stream width, and gradient among reaches surrounding acclimation sites, and canonical correspondence analysis revealed that these differences in habitat characteristics were associated with spatial patterns of spawning (p < 0.01). These analyses indicated that female salmon may forego spawning near their acclimation area if the surrounding habitat is unsuitable. Evaluating the spatial context of acclimation areas in relation to surrounding habitat may provide essential information for effectively managing supplementation programs and prioritizing restoration actions.

IMPORTANCE OF FLOODPLAIN CONNECTIVITY TO FISH POPULATIONS IN THE APALACHICOLA RIVER, FLORIDA

ABSTRACTFloodplain habitats provide critical spawning and rearing habitats for many large‐river fishes. The paradigm that floodplains are essential habitats is often a key reason for restoring altered rivers to natural flow regimes. However, few studies have documented spatial and temporal utilization of floodplain habitats by adult fish of sport or commercial management interest or assessed obligatory access to floodplain habitats for species' persistence. In this study, we applied telemetry techniques to examine adult fish movements between floodplain and mainstem habitats, paired with intensive light trap sampling of larval fish in these same habitats, to assess the relationships between riverine flows and fish movement and spawning patterns in restored and unmodified floodplain distributaries of the Apalachicola River, Florida. Our intent is to inform resource managers on the relationships between the timing, magnitude and duration of flow events and fish spawning as part of river management actions. Our results demonstrate spawning by all study species in floodplain and mainstem river habitat types, apparent migratory movements of some species between these habitats, and distinct spawning events for each study species on the basis of fish movement patterns and light trap catches. Additionally, Micropterus spp., Lepomis spp. and, to a lesser degree, Minytrema melanops used floodplain channel habitat that was experimentally reconnected to the mainstem within a few weeks of completing the restoration. This result is of interest to managers assessing restoration activities to reconnect these habitats as part of riverine restoration programmes globally. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Captive spawning and larval rearing of California yellowtail (Seriola lalandi)

A captive population of California yellowtail (Seriola lalandi) was used to document spawning patterns, including measures of egg production, population fecundity and egg and larval quality from 2007 to 2010. Spawned eggs were also used to document larval development and to develop rearing techniques for aquaculture in the region. Broodstock growth and condition factor were best when feeding rations were maintained at 10–15% body weight week−1 during the warm summer months. A winter ration based on satiation feeding was typically 4% body weight week−1. During the 4-year study period, the only broodstock health issue was an infestation by the parasitic gill fluke Zeuxapta seriolae, which was readily treated. Spawning occurred naturally in the 140 m3 tank when the ambient water temperature reached 16°C and ended when the temperature exceeded 22°C. Egg production reached a maximum in 2010 when 43 spawn events were recorded from a pool of nine females yielding 36.8 million eggs in total. The average female size at this time was 20 kg, which equated to a total annual population fecundity of approximately 226 000 eggs kg−1 female year−1. Larval rearing trials yielded survival rates as high as 5.8% from egg to 50 days post-hatch (dph). Successful larval culture methods included the addition of algae paste for green water culture, rotifers (20 rotifers mL−1) at 2 dph and Artemia (5 Artemia mL−1) at 6 dph. Larvae were transferred from the incubation tank at 10 dph to a shallower tank with 33% greater surface area to accommodate the larvae's strong orientation to surface waters. This research represents the first documentation of successful spawning and larval rearing for S. lalandi in the eastern Pacific.

Reproductive seasonality and annual fecundity in Arcidens confragosus (Unionidae: Unioninae: Anodontini) from Tennessee River, Alabama, USA

Specimens of Arcidens confragosus (Say 1829) were collected monthly from the Tennessee River, Pickwick Reservoir, Alabama, USA, between 21 March 2000 and 26 February 2001. A total of 143 individuals were examined. Microscopic and gross examinations of gonadal and marsupial tissue were used to determine temporal patterns of gamete production, spawning, brooding, and glochidia discharge. In addition, 14 females were collected between October and January to obtain estimates of annual fecundity and three gravid females were used to study internal morphology of gill tissue. The male-to-female sex ratio was equal in the population and individuals reproduced once during their annual cycle. Gametogenesis began in May, peaked in July and August, and spawning occurred between August and September. Embryos were found in September and mature glochidia were brooded between September and February. Fecundity estimates ranged from 75,833–897,500 ( = 408, 452). Secondary water tubes were found within the marsupial gills and were similar to those of other members of the Anodontini.

Reproductive biology of the Japanese butterfish, Psenopsis anomala, in the waters off southwestern Taiwan

The dramatic decline in annual yield of the Japanese butterfish, Psenopsis anomala, in southwestern Taiwan over the past decade suggests that this stock might have been overexploited. However, its fishery biology and stock status is poorly understood. This study therefore provides the first information on P. anomala reproductive biology based on 983 specimens collected by small trawlers in southwestern Taiwan waters between February 1999 and February 2000. The sex ratio, 0.44 (431/983), differed significantly from 0.5 and females predominated in fork length above 180 mm. The relationships between body weight (BW) and fork length (FL) were estimated as BW = 1.62 A— 10−4 A— FL2.637 (r2 = 0.74; n = 430, P < 0.01) for females and BW = 1.28 A— 10−4 A— FL2.671 (r2 = 0.82; n = 552, P < 0.01) for males. Oocytes were mature at 0.5 mm in diameter or larger, and transparent eggs were found at diameters of 0.85 mm. Mean fecundity was estimated at 171 900 ± 61 700 and fecundity (F) was found to increase exponentially with gonad weight (GW) F = 5.4967GW0.511 (n = 132, r2 = 0.74). Mean batch fecundity was estimated to be 83 400 ± 44 600, and relative fecundity from 377 to 2588 (mean 1040) per gram body weight. Logistic curves describing the relationship between proportion of maturity (Pr) at each length interval and fork length were estimated as Pr = 1/(1 + e11.4194−0.0749FL) (r2 = 0.99, n = 351) for females and Pr = 1/(1 + e11.5113−0.0732FL) (r2 = 0.99, n = 258) for males. Size at 50% maturity was estimated as 15.7 and 15.3 cm FL for females and males, respectively. A multi‐spawning pattern was observed in the Japanese butterfish whereby it spawns throughout the year with a peak from February to July. A seasonal closure from April to July (spawning season for most fish species) can provide better breeding opportunities for adults and is believed to be a good fishery management measure for this species.

Documentation of the temporal and spatial patterns of pimelodidae catfish spawning and larvae dispersion in the madre de Dios River (Peru): Insights for conservation in the Andean‐Amazon headwaters

AbstractCatfishes (Siluriformes: Pimelodidae) in the Amazon River Basin serve important ecological and economic roles in structuring foodwebs, transferring nutrients and providing food resources for human populations. Large‐scale developments such as construction of the Interoceanic Highway and associated proposed hydroelectric facilities could lead to alterations in river hydrology and aquatic ecosystems within Amazon headwater regions. We assessed temporal and spatial distribution patterns of catfish larvae to determine spawning location (highlands or lowlands) and larval drift patterns associated with rainfall events in the Andean‐Amazon headwaters. We found significant differences in larval fish catch between transects with highest catches occurring in the Madre de Dios River, suggesting that the primary spawning habitats for these catfishes were in regions upstream of our sampling region within the Peruvian Andes. Highest larval catfish catches generally occurred near shore and in association with seasonal pulses in river flow. Based on our observations, we propose that this section of the Madre de Dios River is near the first identified spawning area for Pimelodidae species in the Peruvian Andes, and from this river reach larvae are transported downstream with each seasonal flood event with peak transport generally occurring in October, November and December. This research documents the important role the Madre de Dios Basin plays as spawning habitat for a key fish family in the Amazon River by serving as a corridor both for adult catfish spawning migrations and downstream larval fish transport. Given the critical role these catfishes play in structuring aquatic ecosystems in the Andean‐Amazon region, their importance as a food resource for local people, and increasing threats to this riverine ecosystem associated with dam construction and channel modification, it is important to maintain and protect natural hydrologic conditions in the Madre de Dios to minimize losses of these ecosystem goods and services. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Reef coral reproduction in the eastern Pacific: Costa Rica, Panamá, and the Galápagos Islands (Ecuador). VI. Agariciidae, Pavona clavus

The reproductive ecology of the zooxanthellate reef coral Pavona clavus was investigated at several sites in Costa Rica, Panama, and the Galapagos Islands (Ecuador) over the period 1985–2009. Pavona clavus displayed stable gonochorism as only five hermaphrodites were found in 590 samples. At four of five locations, sex ratios were skewed toward female dominance; however, at Saboga Island (Panama) male colonies predominated. In Panama, sexual maturity was observed in an estimated eight-year-old female colony, and several colonies of 10–20 years of age demonstrated gametogenesis. Sexual activity was observed at all study sites, but gamete development occurred in only 14–31% of colonies sampled sporadically. Seasonality of gametogenic activity occurred predominantly during the warm/wet season, June to August, at mainland sites (Cano Island, Costa Rica, and Gulfs of Chiriqui and Panama, Panama). This pattern was repeated in the Galapagos Islands, but mainly from March to May when seasonally high sea temperatures and rainfall prevailed there. Histological sampling and field observations indicated that spawning was centered around the full moon, most frequently on lunar day 17, and near sunset (1,800 h). Mean fecundity (mature ova cm−2 live tissue) estimates were significantly different for two sites and ranged from ~1,780 (Saboga Island, Gulf of Panama, seasonally upwelling) to ~4,280 (Uva Is, Gulf of Chiriqui, non-upwelling). Assuming three annual spawning events colony−1 (August, September, October), extrapolation of minimum and maximum fecundities yield 5,340 and 12,840 ova cm−2 year−1. Seasonal, lunar, and diel spawning patterns in nine zooxanthellate species at Uva Island indicate asynchronous coral community spawning.

Seasonal Changes in Reproduction and Biochemical Composition of the Cockle,Fulvia muticaReeve (1884), in Cheonsu Bay off the West Coast of Korea

This is the first study of seasonal changes in gonad development and tissue biochemical composition of the cockle Fulvia mutica in Cheonsu Bay off the west coast of Korea. Gametogenesis commenced in December when the surface water temperature was 9.1°C. In May, the first discharge of oocytes was observed, and spawning continued until October. The condition index (CI), a ratio of tissue dry weight to shell dry weight, increased gradually from late May to July and declined dramatically in August and September, indicating that active discharge of gametes occurred in the bay during this period. Histology and the CI suggested that F. mutica spawning in Cheonsu Bay is continuous from early summer to early fall, with two spawning peaks in June and July, and September and October. All cockles examined in November were sexually inactive. The relatively low CI recorded in late fall to mid winter (November to January) coincided with high levels of ash and low levels of lipids and carbohydrates in the tissue, whereas protein levels remained unchanged. The observed spawning pattern of F. mutica in Cheonsu Bay suggests that the currently established timing for fishing closure, from July to September, should be expanded from June to October to protect earlyspawning broodstocks. This change may secure recruitment and lead to a subsequent increase of the wild cockle population in the bay.