Pelagic Fish Production Research Articles

Dry Me a River: Ecological Effects of Drought in the Upper San Francisco Estuary

Droughts have major effects on estuaries because freshwater entry is one of the defining features of an estuary, and freshwater flow is an important variable that determines the interannual change in the environment. In the upper San Francisco Estuary (the Sacramento–San Joaquin Delta, Suisun Bay, and Suisun Marsh), the Mediterranean climate includes frequent multi-year droughts. To assess ecosystem responses to droughts in the upper estuary, the Interagency Ecological Program Drought Synthesis Team assembled a set of flow, water quality, chlorophyll, zooplankton, and fish data from 1975 to 2021 to test for differences between multi-year droughts and multi-year wet periods and tested for linear relationships between each variable and the Sacramento Valley Hydrologic Index (see definitions and relationships as outlined in Appendix A). Our models showed droughts decreased Delta outflow, project exports, zooplankton in Suisun Bay, and some fish species. We also found that droughts increased water clarity, salinity, nutrients, chlorophyll in the South Delta, zooplankton in the South Delta, and water residence time. Although our analyses only tested correlations, we hypothesized that most of the food-web responses could be traced to increased residence time, decreased transport rates, or both. However, some responses may have been caused by secondary effects, including shifts in salinity gradients, regional changes in water quality, or differences in top-down effects of increased predation and grazing rates. With increased frequency of droughts in the future, this increasingly low-outflow, warming, clearing estuary—which is invaded by non-native species and has low pelagic fish production—is rapidly becoming the new “normal.”

Estimation of The Potential of Large Pelagic Fish Fisheries Using Satellite Data in The Banda and Arafura Seas

The Banda and Arafura Sea possesses significant potential for the fisheries and fishing industry in the country. The large pelagic fish production data studied were derived from satellite imagery data in the Banda and Arafura Seas (2002-2022). The data of chlorophyll-a content, sea surface temperature and Photosynthetically Available Radiation (PAR) derived from AQUA MODIS satellite images were used to estimate the value of primary productivity with the Vertically Generalised Production Model (VGPM). The results showed that the biomass of large pelagic fish fluctuated seasonally, with the Banda Sea and Arafura Sea having high average fish biomass values in the eastern season. With the highest fish biomass peak in August and the lowest in December. The high value of fish biomass in the Banda Sea and Arafura Sea is caused by upwelling events where sea surface temperatures are low but chlorophyll is high. in the Arafura Sea the value of fish biomass is higher than the Banda Sea, this is due to the large amount of nutrient input from large rivers in the area.

Author Correction: No state change in pelagic fish production and biodiversity during the Eocene–Oligocene transition

Author Correction: No state change in pelagic fish production and biodiversity during the Eocene–Oligocene transition

Small pelagic fish in Senegal: a multi-usage resource

The objective of this article is to analyse the marketing of small pelagic fish in Senegal and the issues involved in context of growing national and regional demand and the emergence of new uses, particularly the processing of fish meal. The method consisted of compiling and analysing data (2009–2018) on national small pelagic fish production, foreign trade and the Senegalese population. In Senegal, fish consumption is largely supported by small pelagic fish, which account for 82% of consumption. This represents an average consumption of 13 kg per individual over the period 2009–2018. At the same time, artisanal processing, which is an important element of Senegal's food security, is mainly fed by small pelagics. However, the emergence of non-food uses and export trends of coastal pelagics threaten national food security and the sustainability of small pelagic stocks. Export levels of these species have increased from less than 71,000 tons to over 200,000 tons over the same period coupled with annual industrial non-food processing (fishmeal) of over 20,000 tons. All these mechanisms are responsible for the decline in per capita consumption of small pelagics in Senegal, from 18 kg in 2009 to 9 kg in 2018. As a food safety net in Senegal, the new uses of coastal pelagics threaten the supply of fish products to the local market. The drop in supply to the artisanal processing sector also threatens the employment of thousands of women and compromises their livelihoods.

Statistical Analysis: Marine Capture Production of West Bengal, Andhra Pradesh and Kerala

In this study, basic statistical tools viz., measure of central tendency, dispersion, skewness, correlation and ANOVA tests were applied to analyze the marine capture production data of different groups like Pelagic, Demersal, Crustaceans and Molluscs collected from Marine Products Exports Development Authority, Cochin for the period from 1985 to 2011 pertaining to three costal states of India such as West Bengal, Andhra Pradesh and Kerala. Each group of fish was considered as a treatment for the chosen time series period. Descriptive statistics revealed the elevation of production levels of different groups for states studied. Molluscs production from Andhra Pradesh did not vary much between the years having low standard deviation (918.46) while pelagic fish production varied highly in Kerala having standard deviation (86818.71). In the case of crustaceans, West Bengal had high coefficient of variance (100) and Kerala had low coefficient of variance (19.50) for demersal group. Various kinds of skewed distribution could be observed between groups in all three states. Marine fish productions of different groups from the states of West Bengal and Andhra Pradesh had good correlation except with Kerala where even negative production was observed especially in crustacean production. ANOVA also endorsed that significant production level among various fish groups could be observed in all the states. Similarly, the fish production of every group obtained from the states of West Bengal and Andhra Pradesh differed significantly with Kerala despite no difference in various fish production between the states of West Bengal and Andhra Pradesh could be found.

Study Case: Productivity of Catched Fish in Locations around the Construction of Coal Power Plant, Jepara Indonesia

Background and objective: The productivity of fishing in marine waters provides an overview of the level of ability of the fishing gear used by fishermen to obtain optimal fish catches. This study aims to determine the productivity of fishing in locations around the construction of the coal-fired power plant, Jepara Indonesia.
 Methods: The method used is a descriptive method which is a case study. This research case is about annual marine fishery productivity by calculating Catch Per Unit Effort (CPUE), then predictions are made using simple regression analysis.
 Results: Based on the results of the study, a positive modeling trend (increase) was obtained for total fishery production, total demersal fishery production, and total pelagic fish production.
 Conclusion: capture fisheries productivity in Jepara waters is generally quite good and is not affected due to the development of Tanjung Jati coal-fired power plant B-Unit 5 -6. This is because it is not a fishing operation area for fishermen so there is no potential conflict with fishermen.
 Suggestion: The results of this study can be used by the Government of Jepara Regency in determining sustainable fishing policies and not overfishing

Impact of the Strong Downwelling (Upwelling) on Small Pelagic Fish Production during the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean off Java

Although researchers have investigated the impact of Indian Ocean Dipole (IOD) phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) IOD phases on chlorophyll a (Chl-a) concentrations as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increase) in small pelagic fish production in the EIO off Java.

Enhanced fish production during a period of extreme global warmth

Marine ecosystem models predict a decline in fish production with anthropogenic ocean warming, but how fish production equilibrates to warming on longer timescales is unclear. We report a positive nonlinear correlation between ocean temperature and pelagic fish production during the extreme global warmth of the Early Paleogene Period (62-46 million years ago [Ma]). Using data-constrained modeling, we find that temperature-driven increases in trophic transfer efficiency (the fraction of production passed up trophic levels) and primary production can account for the observed increase in fish production, while changes in predator-prey interactions cannot. These data provide new insight into upper-trophic-level processes constrained from the geological record, suggesting that long-term warming may support more productive food webs in subtropical pelagic ecosystems.

No state change in pelagic fish production and biodiversity during the Eocene–Oligocene transition

The Eocene/Oligocene (E/O) boundary (~33.9 million years ago) has been described as a state change in the Earth system marked by the permanent glaciation of Antarctica and a proposed increase in oceanic productivity. Here we quantified the response of fish production and biodiversity to this event using microfossil fish teeth (ichthyoliths) in seven deep-sea sediment cores from around the world. Ichthyolith accumulation rate (a proxy for fish biomass production) shows no synchronous trends across the E/O. Ichthyolith accumulation in the Southern Ocean and Pacific gyre sites is an order of magnitude lower than that in the equatorial and Atlantic sites, demonstrating that the Southern Ocean was not a highly productive ecosystem for fish before or after the E/O. Further, tooth morphotype diversity and assemblage composition remained stable across the interval, indicating little change in the biodiversity or ecological role of open-ocean fish. While the E/O boundary was a major global climate-change event, its impact on pelagic fish was relatively muted. Our results support recent findings of whale and krill diversification suggesting that the pelagic ecosystem restructuring commonly attributed to the E/O transition probably occurred much later, in the late Oligocene or Miocene. Marine fish biomass and diversity did not change during the Eocene–Oligocene transition despite widespread cooling and Antarctic ice sheet expansion, according to microfossil fish teeth records from a set of deep-sea cores.

Potential, production and utilization level of pelagic fish resource in Ambon City

In responsible and sustainable fisheries, marine resources should be exploited at optimum level in which potency, production and utilization level is known. This research was conducted to analysed potency, production and utilization level of pelagic fish in Ambon Island waters. Data for the analysis was obtained from the secondary data of Dinas Kelautan dan Perikanan Maluku province in the form of catch and effort for period 2005–2015 and then analysed by using Schaefer model. Estimated Maximum Sustainable Yield (MSY) was 103,513 tons with Total Allowable Catch (TAC) was 82,811 tons. Production of pelagic fish fluctuated but tended to increase due to increasing of fishing vessels and fishing gears. Catch per unit effort of purse seine and pole and line contributed more for the pelagic fish production than five other fishing gears. The utilization of pelagic fish resources in Ambon tended to increase with annual average 61.7% from TAC or 49.40% of MSY during the period of 2005-2015. In the last three years (2013-2015) the level of utilization increased significantly and has reached 98.31% from TAC or 78.65% of MSY which leads to fully exploitation. These results indicated that fishing effort should be maintained and monitored strictly to prevent over exploitation of pelagic fish resource.

Karakteristik Fisika dan Kimia Perairan di Laut Jawa – Ambang Dewakang

<strong>Physical and Chemical Properties of Waters in Java – Ambang Dewakang Sea</strong>.The Java Sea is a region of important pelagic fish production in Indonesia. The distribution of abundance of fish is affected by changes in water physical and chemical properties. The important chemical property that can affect the abundance of the fish is the availability of nutrients. Nutrients are the basic compounds of marine biogeochemical cycles that play important role in increasing aquatic productivity through growth of the phytoplankton. The purposes of this study are to know recent condition of chemical and physical characteristics of the sea water within the region Java Sea ‒ Ambang Dewakang and to investigate relationships among these parameters. This research was conducted in November 2014 at 7 stations in the region. The observed parameters were physical (temperature, salinity, turbidity, density) and chemical such as nutrients (DIN, PO<sub>4</sub>-P, SiO<sub>3</sub>-Si), pH, and DO. CTD (<em>Conductivity-Temperature-Depth</em>) SBE (<em>Sea Bird Electronics</em>) 911 Plus was used to measure water physical properties. Water sample was collected using Rosette sampler, while analysis of nutrients concentration employed methods from Strickland and Parsons 1972. The result showed that temperatures in the Java Sea ranged from 13.06 – 30.33 °C with an average of 25.29 °C, whereas salinity ranged between 33.07 – 34.74 psu with an average of 34.41 psu. Variations within temperature and salinity showed a homogeneous condition due to the influence of mixing processes. Concentration range of DIN (NO<sub>3</sub>-N+NO<sub>2</sub>-N+NH<sub>4</sub>-N), PO<sub>4</sub>-P, SiO<sub>3</sub>-Si were from 0.070 to 0.180 mg/L, from 0.004 to 0.022 mg/L and from 0.082 to 0.361 mg/L, with an average of 0.096 mg/L, 0.010 mg/L, and 0.159 mg/L respectively. The ratio DIN/DIP of 13.24 showed that the waters quality of Java Sea was in the moderate category.

Application of modified atmosphere packaging on aquacultured fish and fish products: A review

The aquaculture industry has undergone a rapid and continuous growth during the last decade due to increased demands in seafood consumption and reduced pelagic fish production. The aquaculture sector can provide products with a consistent flow and quality standards to cover the market's needs. The modified atmosphere packaging (MAP) technique has evolved over the last two decades and many reports indicate its beneficial effect on many quality parameters during fish and shellfish preservation. The use of MAP can clearly offer an advantage to the safer distribution of quality aquacultured fishery products. This article summarizes most of the experimental data of packaging techniques applied (MAP, VP, various pretreatments and packaging materials) on aquacultured fish and fish products to provide a clear view of the potential for a future commercial use.

Patterns in the crustacean zooplankton community in Lake Winnipeg, Manitoba: Response to long-term environmental change

Changes in the crustacean zooplankton community composition and abundance in Lake Winnipeg (1969–2006) provide a rare opportunity to examine their response to environmental changes in the largest naturally eutrophic lake on the Canadian prairies. Since 1929, zooplankton species composition in Lake Winnipeg has changed little except for the addition of the invasive cladoceran, Eubosmina coregoni in 1994. The dominant taxa in the lake in summer include: Leptodiaptomus ashlandi, Acanthocyclops vernalis, Diacyclops thomasi, Daphnia retrocurva, Daphnia mendotae, Diaphanosoma birgei, Eubosmina coregoni, and Bosmina longirostris. Climate-accelerated nutrient loading to southern Lake Winnipeg over the last two decades has led to increased phytoplankton abundance and higher frequency of cyanobacterial blooms especially in its northern basin. Crustacean zooplankton have likewise increased especially in the North Basin, but less so in the more nutrient rich South Basin, possibly as a consequence of higher densities of pelagic planktivorous fish and light-limited primary production compared with the more transparent North basin (Brunskill et al., 1979, 1980). Calanoid copepods play a larger role in the South basin food web in contrast to cyclopoid copepods and Cladocera in the North basin. The study begins to fill the recognized gap in understanding of Lake Winnipeg's food web structure and provides a baseline for evaluating ongoing changes in the zooplankton community with the arrival of new non-indigenous taxa, e.g. Bythotrephes longimanus and Dreissena polymorpha. It reinforces previous work demonstrating that zooplankton provide valuable indices toward evaluating the health of an ecosystem.

Effects of hypoxia on habitat quality of pelagic planktivorous fishes in the northern Gulf of Mexico

To evaluate the impact of hypoxia (<2 mg O2 l �1 ) on habitat quality of pelagic prey fishes in the northern Gulf of Mexico, we used a spatially explicit, bioenergetics-based growth rate potential (GRP) model to develop indices of habitat quality. Our focus was on the pelagic bay anchovy Anchoa mitchilli and Gulf menhaden Brevoortia patronus. Positive GRP was considered high-quality habitat (HQH) and negative GRP was considered low-quality habitat (LQH). Models used water temperature, dissolved oxygen (DO), zooplankton biomass, and phytoplankton con- centration collected during the peak periods of hypoxia in 2003, 2004, and 2006 to estimate fish GRP. Results showed that hypoxic areas were always LQH. However, with respect to the entire water column, hypoxia had only a minor impact on overall habitat quality, with habitat quality being driven primarily by prey availability followed by water temperature. These results are in contrast to other ecosystems, such as the Chesapeake Bay, where hypoxia affects a larger fraction of the water column than in the Gulf of Mexico and has a significant impact on overall habitat quality. Differences in the effect of hypoxia on habitat quality between these 2 ecosystems suggest that the vertical extent of hypoxia relative to water column depth (i.e. hypoxic volume) is a funda- mental consideration when evaluating the impacts of hypoxia on pelagic fish production.

Dividing up the pie: Whales, fish, and humans as competitors

Similarly structured food web models of four coastal ecosystems (Northern California Current, Central Gulf of Alaska, Georges Bank, southwestern Antarctic Peninsula) were used to investigate competition among whales, fishes, pinnipeds, and humans. Two analysis strategies simulated the effects of historic baleen and odontocete whale abundances across all trophic levels: food web structure scenarios and time-dynamic scenarios. Direct competition between whales and commercial fisheries is small at current whale abundances; whales and fisheries each take similar proportions of annual pelagic fish production (4–7%). Scenarios show that as whale populations grow, indirect competition between whales and fish for zooplankton would more likely impact fishery production than would direct competition for fish between whales and commercial fisheries. Increased baleen whale abundance would have greater and broader indirect effects on upper trophic levels and fisheries than a similar increase in odontocete abundance. Time-dynamic scenarios, which allow for the evolution of compensatory mechanisms, showed more modest impacts than structural scenarios, which show the immediate impacts of altered energy pathways.Structural scenarios show that in terms of energy availability, there is potential for large increases in whale abundance without major changes to existing food web structures and without substantial reduction of fishery production. For each ecosystem, a five-fold increase in baleen whale abundance could be supported with minor disruptions to existing energy flow pathways. However, such an increase would remain below historical population levels for many cetaceans. A larger expansion (20X) could be accommodated only with large reductions in energy flow to competitor groups. The scope for odontocete expansion varies between ecosystems but may be more restricted than the scope for baleen expansion because they feed at higher, less productive trophic levels.

Secondary production of Chironomidae in a large eutrophic lake: implications for lake sturgeon production

Abstract. Most foodweb research in lentic systems has focused on pelagic primary (phytoplankton) and secondary (zooplankton) production as the primary energy sources for higher trophic-level production. Recent research has demonstrated that secondary production of benthic primary consumers can affect pelagic fish production and foodweb structure in lakes. We used the instantaneous growth method to calculate secondary production of chironomids in Lake Winnebago, Wisconsin (USA), where previous research has shown that lake sturgeon (Acipenser fulvescens) rely heavily on the benthos (chironomids) as a food source. We also used literature-derived data and the instantaneous growth method to calculate annual production of lake sturgeon to test whether chironomid production is sufficient to support the current lake sturgeon population in Lake Winnebago. We collected benthic samples with an Ekman grab at 4 profundal sites during ice-free conditions on 11 dates from spring 2008 through spring 2009. We measured in...

Climate modulation of fish populations: the role of the Western Mediterranean Oscillation (WeMO) in sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) production in the north-western Mediterranean

This study investigates the connections between climate fluctuations and sardine and anchovy production in the NW Mediterranean, taking the Western Mediterranean Oscillation index (WeMOi) as an indicator of climate variability. The basic working hypothesis is that sardine and anchovy productivity is influenced by the WeMOi, a proxy for the local environmental conditions such as sea surface temperature (SST) and river runoff. Sardine and anchovy landings (1974–2009) in the Catalan Coast and landings per unit of effort (LPUE) were used as proxy for recruitment. The results demonstrated a clear link between climate fluctuations and sardine and anchovy production. Positive WeMOi values were significantly correlated with low SST, high river runoff and high LPUE, that is, with better-than-average recruitment of sardine and anchovy. Conversely, negative WeMOi values were associated with high SST, low river runoff and low LPUE. During the negative WeMOi phases (such as that at the end of the analyzed period), environmental conditions are unfavourable for the overall biological productivity in the NW Mediterranean and would decrease the survival, growth, condition and reproduction of sardine and anchovy during their life cycle. Despite the evidences on the appropriateness of the NAOi as an indicator of the climate in Europe and its impact on some biological variables, we suggest that using a regional index, such as the WeMOi, can provide a more accurate representation of the environmental conditions affecting small pelagic fish production in the NW Mediterranean.

Influence of planktonic foodweb structure on a system's capacity to support pelagic production: an inverse analysis approach

Abstract Marquis, E., Niquil, N., Vézina, A. F., Petitgas, P., and Dupuy, C. 2011. Influence of planktonic foodweb structure on a system's capacity to support pelagic production: an inverse analysis approach. – ICES Journal of Marine Science, 68: 803–812. Coupled plankton/small pelagic (SP) fish systems were analysed to assess how foodweb structure influences the export of carbon to pelagic fish during the spring bloom in the Bay of Biscay. The investigation of carbon export flows through inverse analysis was supplemented by estimating the carrying capacity for pelagic fish production by applying linear programming. A planktonic foodweb dominated by microbial pathways had the highest trophic efficiency owing to the tight coupling between planktonic trophic levels and predation pressure on mesozooplankton by fish. Moreover, the magnitude of the gap between carrying capacity and estimated carbon export was related to the size structure of primary producers, with the picophytoplankton-based foodweb having the smallest gap and the microphytoplankton-based one the largest gap. Planktonic foodwebs dominated by small autotrophic cells channelled most of their available carbon to pelagic fish production, whereas foodwebs dominated by large phytoplankton were better suited to benthic communities with a large loss of carbon through sedimentation. Although the total carbon available to higher trophic levels does not vary with the size of the main primary producers, the potential export to SP fish depends on the structure of the planktonic foodweb.

Modeling and forecasting pelagic fish production using univariate and multivariate ARIMA models

Univariate and multivariate autoregressive integrated moving average (ARIMA) models were used to model and forecast the monthly pelagic production of fish species in the Mediterranean Sea during 1990–2005. Autocorrelation (AC) and partial autocorrelation (PAC) functions were estimated, which led to the identification and construction of seasonal ARIMA models, suitable in explaining the time series and forecasting the future catch per unit of effort (CPUE) values. Univariate and multivariate ARIMA models satisfactorily predicted the total pelagic fish production and the production of anchovy, sardine, and horse mackerel. The univariate ARIMA models demonstrated a good perpormance in terms of explained variability and predicting power. The current findings revealed a strong autoregressive character providing relatively high R 2 and satisfactory forecasts that were close to the recorded CPUE values. The present results also indicated that the multivariate ARIMA outperformed the univariate ARIMA models in terms of fitting accuracy. The opposite was evidenced when testing the forecasting accuracy of the two methods, where the univariate ARIMA models overall performed better than the multivariate models. The observed seasonal pattern in the monthly production series was attributed to the intrinsic nature of the pelagic fishery. As anchovy, sardine, and horse mackerel represent main target species in the Mediterranean pelagic fishery, the findings of the present study provided direct support for the potential use of accurate forecasts in decision making and fisheries management in the Mediterranean Sea.

The Economics of a 'Mixed Blessing' Effect: A Case Study of the Black Sea

Nutrient enrichment of marine ecosystems is regarded as a pressing global environmental problem. For certain marine species it may be a mixed blessing, resulting in damaging ecosystem events, but contributing to primary productivity. Consequently, the impact of enrichment on fishery profits may be positive or negative. This paper develops a method for analyzing such problems, using the example of the Black Sea anchovy fishery. Employing a bioeconomic model that incorporates nutrients directly into fish population dynamics, the problem is formulated in deterministic and stochastic terms. The deterministic model assumes a given ecological state in which nutrients contribute positively to pelagic fish production. The stochastic model recognizes that the planner may take into account the probability of potentially damaging shifts in ecological states due to nutrient enrichment. In this latter model, nutrient abatement has an indeterminate welfare effect, but under certain conditions a marginal change in nutrients generates positive aggregate benefits.