Tidal and diel influence on zooplankton occurrence in the Mandovi estuary, Goa

Distribution and abundance of zooplankton over the tidal cycle were studied in the Mandovi estuary, Goa, during August and December 1971 and May 1972. Tide induced salinity fluctuations were obvious with high values during spring tides. Salinity was low during August, apparently due to precipitation and land run off but increased subsequently. The mean biomass values for the day and night collections were 13.6 and 19.8 ml/100 m super(3) respectively. Occurrence of most of the zooplankton taxa and species was related to diel rhythm and tidal oscillations. However, overall mean zooplankton standing stock at both the stations were same (16.3 ml/100 m super(3)) indicating that estuarine zooplankton maintained their position during tidal exchanges. Variations in occurrence of common groups and species of zooplankton over the tidal cycle are discussed.

Seasonal variability in penaeid prawn larval abundance in the Mandovi and Zuari estuaries, Goa

Seasonal variations in the occurrence and abundance of penaeid prawn larvae in the Mandovi and Zuari estuaries of Goa were studied. Larvae and post-larvae of commercially important species viz. Metapenaeus dobsoni (Miers), M.affinis (H. Milne Edwards). M. Monoceros (Fabricius), Penaeus merguiensis de Man and Parapenaeopsis stylifera (H. Milne Edwards) were recorded in that order of abundance. Protozoea and mysis stages were dominant in surface zooplankton collections while the post-larvae were more in the bottom samples. Based on larval density, M. dobsoni appeared to be a continuous breeder. The active spawning periods in other species were during the late post-monsoon and pre-monsoon seasons varying with the species. Peak recruitment of post-larvae in the estuaries was observed mostly during southwest monsoon months (June to September). Penaeid prawn larval ingression was more in the Zuari estuary compared to the Mandovi estuary. Their numerical abundance gradually decreased towards the upstream areas. The feasibility of large scale collection of penaeid prawn larvae for aquaculture is indicated.

A new record of two penaeid species from Goa coast

Adults of Penaeus japonicus (Bate) and juveniles of P. canaliculatus (Olivier) were recorded for the first time from the coastal and estuarine regions of Goa respectively. Their presence in Goa waters suggests that both the species have a wide distribution along the west coast of India. The available data from the neighboring states suggest that both the species are distributed in deeper waters and are caught during or immediately after the southwest monsoon. Hence, it may be possible to tap these valuable resources from Goa waters if the fishing operation is extended to depths beyond those presently fished and fishing is carried out during the SW monsoon season.

Ecology and production in two sandy beaches of Goa. Part (A) Distribution of bacteria in Colva and Siridaon in relation to certain environmental parameters

Qualitative and quantitative studies on the bacterial flora of two beaches viz., Colva and Siridaon at high tide, mid-tide and low tide levels during the pre-monsoon period were made. Estimations of important nutrients, like inorganic phosphates and nitrates and organic carbon have been made and correlation with the bacterial counts is being attempted. Definite correlation between bacterial population and organic carbon is seen however, no correlation is observed between bacterial counts and other physicochemical parameters.

Purse-seines off Goa

The design, construction and operational details of the purse-seines operated from Goa, for sardines and mackerel are reported briefly. The deck equipment and details of vessel along with the fishing season, fishing grounds and catches are briefly accounted. The design has been compared with Japanese purse-seines operated for the same species of fishes. Based on the findings an improved design of purse-seine has been presented.

Report of the workshop on ecosystem characterisation of Indian coastal waters, Dona Paula, Goa, India, 20-22 October, 2014

The goals of the workshop were to: conduct an interactive workshop for characterizing Indian coastal ecosystems; verification of the ecosystem characterisation report for the East coast of India; and development of ecosystem characterisation for the west coast of India based on ecological/biophysical systems.

Report of the Study Group on “ Fisheries and Ecosystem Response to Recent Regime Shifts”

EXECUTIVE SUMMARY 1. DECADAL-SCALE CLIMATE EVENTS 1.1 Introduction 1.2 Basin-scale Patterns 1.3 Long Time Series in the North Pacific 1.4 Decadal Climate Variability in Ecological Regions of the North Pacific 1.5 Mechanisms 1.6 References 2. COHERENT REGIONAL RESPONSES 2.1 Introduction 2.2 Central North Pacific (CNP) 2.3 California Current System (CCS) 2.4 Gulf of Alaska (GOA) 2.5 Bering Sea and Aleutian Islands 2.6 Western North Pacific (WNP) 2.7 Coherence in Regional Responses to the 1998 Regime Shift 2.8 Climate Indicators for Detecting Regime Shifts 2.9 References 3. IMPLICATIONS FOR THE MANAGEMENT OF MARINE RESOURCES 3.1 Introduction 3.2 Response Time of Biota to Regime Shifts 3.3 Response Time of Management to Regime Shifts 3.4 Provision of Stock Assessment Advice 3.5 Decision Rules 3.6 References 4. SUGGESTED LITERATURE 4.1 Climate Regimes 4.2 Impacts on Lower Trophic Levels 4.3 Impacts on Fish and Higher Trophic Levels 4.4 Impacts on Ecosystems and Possible Mechanisms 4.5 Regimes and Fisheries Management APPENDIX 1: RECENT ECOSYSTEM CHANGES IN THE CENTRAL NORTH PACIFIC A1.1 Introduction A1.2 Physical Oceanography A1.3 Lower Trophic Levels A1.4 Invertebrates A1.5 Fishes A1.6 References APPENDIX 2: RECENT ECOSYSTEM CHANGES IN THE CALIFORNIA CURRENT SYSTEM A2.1 Introduction A2.2 Physical Oceanography A2.3 Lower Trophic Levels A2.4 Invertebrates A2.5 Fishes A2.6 References APPENDIX 3: RECENT ECOSYSTEM CHANGES IN THE GULF OF ALASKA A3.1 Introduction A3.2 Physical Oceanography A3.3 Lower Trophic Levels A3.4 Invertebrates A3.5 Fishes A3.6 Higher Trophic Levels A3.7 Coherence in Gulf of Alaska Fish A3.8 Combined Standardized Indices of Recruitment and Survival Rate A3.9 References APPENDIX 4: RECENT ECOSYSTEM CHANGES IN THE BERING SEA AND ALEUTIAN ISLANDS A4.1 Introduction A4.2 Bering Sea Environmental Variables and Physical Oceanography A4.3 Bering Sea Lower Trophic Levels A4.4 Bering Sea Invertebrates A4.5 Bering Sea Fishes A4.6 Bering Sea Higher Trophic Levels A4.7 Coherence in Bering Sea Fish Responses A4.8 Combined Standardized Indices of Bering Fish Recruitment and Survival Rate A4.9 Aleutian Islands A4.10 References APPENDIX 5: RECENT ECOSYSTEM CHANGES IN THE WESTERN NORTH PACIFIC A5.1 Introduction A5.2 Sea of Okhotsk A5.3 Tsushima Current Region and Kuroshio/Oyashio Current Region A5.4 Bohai Sea, Yellow Sea, and East China Sea A5.5 References (168 page document)

Contrasting abundance and residency patterns of two sympatric populations of transient killer whales (Orcinus orca) in the northern Gulf of Alaska

Two sympatric populations of “transient” (mammal-eating) killer whales were photo-identified over 27 years (1984–2010) in Prince William Sound and Kenai Fjords, coastal waters of the northern Gulf of Alaska (GOA). A total of 88 individuals were identified during 203 encounters with “AT1” transients (22 individuals) and 91 encounters with “GOA” transients (66 individuals). The median number of individuals identified annually was similar for both populations (AT1=7; GOA=8), but mark-recapture estimates showed the AT1 whales to have much higher fidelity to the study area, whereas the GOA whales had a higher exchange of individuals. Apparent survival estimates were generally high for both populations, but there was a significant reduction in the survival of AT1 transients after the Exxon Valdez oil spill in 1989, with an abrupt decline in estimated abundance from a high of 22 in 1989 to a low of seven whales at the end of 2010. There was no detectable decline in GOA population abundance or survival over the same period, but abundance ranged from just 6 to 18 whales annually. Resighting data from adjacent coastal waters and movement tracks from satellite tags further indicated that the GOA whales are part of a larger population with a more extensive range, whereas AT1 whales are resident to the study area.

Age- and length-at-maturity of female arrowtooth flounder (Atheresthes stomias) in the Gulf of Alaska

Arrowtooth flounder (Atheresthes stomias) has had the highest abundance of any groundfish species in the Gulf of Alaska since the 1970s (Matarese et al., 2003; Turnock et al., 2005; Blood et al., 2007); however, commercial catches have been restricted because Pacific halibut (Hippoglossus stenolepis) are caught as bycatch in the fishery. Arrowtooth flounder plays a key role in the ecosystem because it is a dominant organism within the food web, both as an apex predator of fish and invertebrates, as well as an important prey for walleye pollock (Theragra chalcogramma; Aydin et al., 2002). Walleye pollock is the dominant groundfish in the Bering Sea, a principal groundfish in the Gulf of Alaska, and the primary prey for marine mammals. The distribution of arrowtooth flounder extends from Cape Navarin and the eastern Sea of Okhotsk in Russia, across the Bering Sea, Aleutian Islands, Gulf of Alaska, and south to the coast of central California (Shuntov, 1964; Britt and Martin, 2001; Chetvergov, 2001; Weinberg et al., 2002; Zenger, 2004). Because of the importance of arrowtooth flounder in the marine ecosystem of A laska, a maturity study of this species was undertaken to determine age-at-maturity, which is essential for age-based stock management models. Before these results, management has had to rely upon a length-at-maturity-based estimate (Zimmermann, 1997) to manage stocks in the Gulf of Alaska (GOA), Bering Sea, and Aleutian Islands. The central GOA was selected as the location for this maturity study Age- and length-at-maturity of female arrowtooth flounder (Atheresthes stomias) in the Gulf of Alaska because it contains approximately 70% of the total Gulf of Alaska arrowtooth flounder biomass (1.9×106 t, age 3 and older)— the highest percentage in the world (Shuntov, 1964; Britt and Martin, 2001; Weinberg et al., 2002; Wilderbuer and Nichol, 2006).

Reproductive biology, spawning season, and growth of female rex sole (Glyptocephalus zachirus) in the Gulf of Alaska

Rex sole (Glyptocephalus zachirus) have a wide distribution throughout the North Pacific, ranging from central Baja California to the western Bering Sea. Although rex sole are an important species in the commercial trawl fisheries off the U.S. West Coast, knowledge of their reproductive biology is limited to one study off the Oregon coast where ovaries were analyzed with gross anatomical methods. This study was initiated to determine reproductive and growth parameters specific to rex sole in the Gulf of Alaska (GOA) stock. Female rex sole (n=594) ranging in total length from 166 to 552 mm were collected opportunistically around Kodiak Island, Alaska, from February 2000 to October 2001. All ovaries were analyzed by using standard histological criteria to determine the maturity stage. Year-round sampling of rex sole ovaries confirmed that rex sole are batch spawners and have a protracted spawning season in the GOA that lasts at least eight months, from October to May; the duration of the spawning season and the months of spawning activity are different from those previously estimated. Female rex sole in the GOA had an estimated length at 50% maturity (ML50) of 352 mm, which is greater than the previously estimated ML50 at southern latitudes. The maximum age of collected female rex sole was 29 years, and the estimated age at 50% maturity (MA50) in the GOA was 5.1 years. The von Bertalanffy growth model for rex sole in the GOA was significantly different from the previously estimated model for rex sole off the Oregon coast. This study indicated that there are higher growth rates for rex sole in the GOA than off the Oregon coast and that there are differences in length at maturity and similarity in age at maturity between the two regions.

SAMUDRA Report No. 64, March 2013

Contents: At a crossroads: England’s small-scale fisheries are being integrated within a national system. Diversionary tactics: Most of Peru’s anchoveta catches meant for human consumption are being diverted. Fair, sustainable? The new EU-Mauritania Fisheries Agreement has been welcomed—and spurned. A weighty responsibility: A fisheries reform process is under way in several parts of Africa. Sri Lanka. Restoring past glory: The Regional Fisheries Livelihoods Programme focuses on fisheries in the Negombo lagoon. Need for vigilance: Summary of a study on globalization and trade treaties in Atlantic Canadian fisheries. A collective voice: A national workshop on the ILO Work in Fishing Convention was held in Goa, India. Short-term model: Brazil is backing increased production through industrial fisheries and aquaculture. Living the learning. 70 participants from the Honduran Caribbean coast gathered at a conference on SSF. Brazil. Towards synthesis: On the approach of civil society organizations towards the proposed SSF Guidlines.

A geo-referenced benthic habitat survey in support of natural resource management: Port Graham Bay, Alaska

The impact of recent changes in climate on the arctic environment and its ecosystems appear to have a dramatic affect on natural populations (National Research Council Committee on the Bering Sea Ecosystem 1996) and pose a serious threat to the continuity of indigenous arctic cultures that are dependent on natural resources for subsistence (Peterson D. L., Johnson 1995). In the northeast Pacific, winter storms have intensified and shifted southward causing fundamental changes in sea surface temperature patterns (Beamish 1993, Francis et al. 1998). Since the mid 1970’s surface waters of the central basin of the Gulf of Alaska (GOA) have warmed and freshened with a consequent increase in stratification and reduced winter entrainment of nutrients (Stabeno et al. 2004). Such physical changes in the structure of the ocean can rapidly affect lower trophic levels and indirectly affect fish and marine mammal populations through impacts on their prey (Benson and Trites 2002). Alaskan natives expect continued and perhaps accelerating changes in resources due to global warming (DFO 2006).and want to develop strategies to cope with their changing environment.

Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996

Triennial bottom trawl survey data from 1984 to 1996 were used to evaluate changes in the summer distribution of walleye pollock in the western and central Gulf of Alaska. Differences between several age groups of pollock were evaluated. Distribution was examined in relation to several physical characteristics, including bottom depth and distance from land. Interspecies associations were also analyzed with the Bray-Curtis clustering technique to better understand community structure. Our results indicated that although the population numbers decreased, high concentrations of pollock remained in the same areas during 1984–96. However, there was an increase in the number of stations where low-density pollock concentrations of all ages were observed, which resulted in a decrease in mean population density of pollock within the GOA region. Patterns emerging from our data suggested an alternative to Mac-Call’s “basin hypothesis” which states that as population numbers decrease, there should be a contraction of the population range to optimal habitats. During 1984–96 there was a concurrent precipitous decline in Steller sea lions in the Gulf of Alaska. The results of our study suggest that decreases in the mean density of adult pollock, the main food in the Steller sea lion diet, combined with slight changes in the distribution of pollock (age-1 pollock in particular) in the mid-1980s, may have contributed to decreased foraging efficiency in Steller sea lions. Our results support the prevailing conceptual model for pollock ontogeny, although there is evidence that substantial spawning may also occur outside of Shelikof Strait.

Spatial and temporal patterns in the demersal fish community on the shelf and upper slope regions of the Gulf of Alaska

We analyzed data from National Marine Fisheries Service bottom trawl surveys carried out triennially from 1984 to 1996 in the Gulf of Alaska (GOA). The continental shelf and upper slope (0–500 m) of the GOA support a rich demersal fish fauna dominated by arrowtooth flounder (Atheresthes stomias), walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and Pacific Ocean perch (Sebastes alutus). Average catch per unit of effort (CPUE) of all groundfish species combined increased with depth and had a significant peak near the shelf break at 150–200 m. Species richness and diversity had significant peaks at 200–300 m. The western GOA was characterized by higher CPUEs and lower species richness and diversity than the eastern GOA. Highest CPUEs were observed in Shelikof Strait, along the shelf break and upper slope south of Kodiak Island, and on the banks and in the gullies northeast of Kodiak Island. Significant differences in total CPUE among surveys suggest a 40% increase in total groundfish biomass between 1984 and 1996. A multivariate analysis of the CPUE of 72 groundfish taxa revealed strong gradients in species composition with depth and from east to west, and a weak but significant trend in species composition over time. The trend over time was associated with increases in the frequency of occurrence and CPUE of at least eight taxa, including skates (Rajidae), capelin (Mallotus villosus), three flatfish species, and Pacific Ocean perch, and decreases in frequency of occurrence and CPUE of several sculpin (Myoxocephalus spp.) species. Results are discussed in terms of spatial and temporal patterns in productivity and in the context of their ecological and management implications.

Rice-fish culture: status and potential for increased production in the southwestern states of India

The scope of increasing production through rice-fish integration, suitable for coastal districts of Kerala, Karnataka, Goa and Maharashtra, is reviewed. The method of adopting the lowlying freshwater rice fields to raise 2 rice crops along with 4-species fish culture, followed by a third non-cereal summer crop in a year, is discussed. A calendar of operation and economics of the system are presented.