Predicting the recruitment strength of an annual squid stock: Loligo gahi around the Falkland Islands

2000 ◽  
Vol 57 (12) ◽  
pp. 2479-2487 ◽  
Author(s):  
David J Agnew ◽  
Simeon Hill ◽  
John R Beddington
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Negative Relationship ◽  
Sea Surface ◽  
Falkland Islands ◽  
Factors Affecting ◽  
Model Combining ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Faster Development

Two cohorts of Loligo gahi recruit to the fishery around the Falkland Islands, the first in summer and the second in autumn-winter. We investigated factors affecting recruitment to these cohorts using 13 years of data (1987-1999). The first evidence for density-dependent effects on recruitment in a squid population is reported, with very high spawning stock biomass leading to a reduction in recruitment in both cohorts. October sea surface temperature was negatively correlated with recruitment to the second cohort 6 months later, and a linear model explained 66% of the variance in recruitment strength. A model combining sea surface temperature and spawning stock size explained 77% of the variance. Thus, low October temperatures and moderate stock sizes lead to higher recruitment the following year than high October temperatures and high stock sizes. A strong negative relationship was also found between sea surface temperature in May and the timing of recruitment to the first cohort the following January-February, suggesting that higher temperatures lead to faster development of embryos or paralarvae and earlier recruitment to the fishery. A predictive model of recruitment size and timing should enable better management of L. gahi.

scholarly journals Diet shifts of Rhizoprionodon terraenovae from the southern Gulf of Mexico: possible scenario by temperature changes

2020 ◽  
Vol 48 (3) ◽  
pp. 406-420
Author(s):  
Javier E. Viana-Morayta ◽  
Yassir E. Torres-Rojas ◽  
Jaime Camalich-Carpizo
Keyword(s):  
Body Size ◽  
Gulf Of Mexico ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Trophic Level ◽  
Negative Relationship ◽  
Diet Breadth ◽  
Sea Surface ◽  
Rhizoprionodon Terraenovae ◽  
Southern Gulf Of Mexico

The current study examined the stomach contents of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) in the southern Gulf of Mexico during 2015 to understand the relationship between diet and changes in sea surface temperature (SST). Prey-specific index of relative importance (%PSIRI), diet breadth (Bi), trophic level (TrL), and trophic overlap (PERMANOVA) were calculated between sexes, body size, and climatic seasons (dry, rainy and winter storm). The lowest temperature recorded in the area was during February (23.9°C), and the highest was during August (29.1°C). A total of 124 stomachs were analyzed, with 54.84% containing food. The trophic spectrum was composed of 32 identified prey, with demersal fish (Haemulon plumierii; %PSIRI = 22.82) and pelagic fish (Sardinella aurita; %PSIRI = 12.83) being the most important. According to the diet breadth (Bi = 0.002), Costello's graph, and trophic level (TrL = 4.2), R. terraenovae is a specialist tertiary consumer. PERMANOVA indicated significant trophic differences between sexes (F = 32.22; P < 0.05), body size (F = 13.68; P < 0.05), and among climatic seasons (F = 23.86; P < 0.05). Spearman's correlation indicated a negative relationship between the diversity of prey consumed by R. terraenovae and sea surface temperature (r = -0.75; P < 0.05). Therefore, diet for R. terraenovae is associated with SST, allowing for the development of possible scenarios related to climatic phenomena like climate change.

scholarly journals Assessing causal links in fish stock–recruitment relationships

2017 ◽  
Vol 75 (3) ◽  
pp. 903-911 ◽  
Author(s):  
Maud Pierre ◽  
Tristan Rouyer ◽  
Sylvain Bonhommeau ◽  
J M Fromentin
Keyword(s):  
Time Series ◽  
Dynamical Systems ◽  
Surface Temperature ◽  
Sea Surface ◽  
Fish Stock ◽  
Stochastic Forcing ◽  
Forecasting Methods ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Stock Recruitment

Abstract Understanding whether recruitment fluctuations in fish stock arise from stochastic forcing (e.g. environmental variations) rather than deterministic forces (e.g. intrinsic dynamics) is a long standing question with important applied consequences for fisheries ecology. In particular, the relationship between recruitment, spawning stock biomass and environmental factors is still poorly understood, even though this aspect is crucial for fisheries management. Fisheries data are often short, but arise from complex dynamical systems with a high degree of stochastic forcing, which are difficult to capture through classic modelling approaches. In the present study, recent statistical approaches based on the approximation of the attractors of dynamical systems are applied on a large dataset of time series to assess (i) the directionality of potential causal relationships between recruitment and spawning stock biomass and potential influence of sea-surface temperature on recruitment and (ii) their performance to forecast recruitment. Our study shows that (i) whereas spawning stock biomass and sea surface temperature influence the recruitment to a lesser extent, recruitment causes also parental stock size and (ii) that non-linear forecasting methods performed well for the short-term predictions of recruitment time series. Our results underline that the complex and stochastic nature of the processes characterizing recruitment are unlikely to be captured by classical stock–recruitment relationships, but that non-linear forecasting methods provide interesting perspectives in that respect.

Growth and Maturation of Pacific Herring (Clupea harengus pallasi) in the Strait of Georgia

1985 ◽  
Vol 42 (S1) ◽  
pp. s138-s146 ◽  
Author(s):  
V. Haist ◽  
M. Stocker
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Clupea Harengus ◽  
Sea Surface ◽  
Pacific Herring ◽  
Juvenile Growth ◽  
Strait Of Georgia ◽  
Surplus Energy ◽  
Clupea Harengus Pallasi ◽  
Stock Biomass

Juvenile growth rate, adult surplus energy, and the maturation schedule for the Strait of Georgia Pacific herring (Clupea harengus pallasi) stock were investigated over the period 1950–81. The variance in weight at age 2 is largely accounted for by juvenile abundance and sea surface temperature, indicating density-dependent juvenile growth moderated by environmental factors. Density and environmental factors have been equally important in moderating juvenile growth. Yearly variation in maturation of 3-yr-old herring is related to their average length; however, in two of the eight years studied the 3-yr-olds matured at considerably smaller sizes. The variance in adult surplus energy (growth plus gonad production) was largely accounted for by body weight, adult biomass, and sea surface temperature. A dome-shaped relationship between surplus energy and biomass was indicated, suggesting that over a broad range of population size, adult surplus energy is not density dependent. The relationship of sea surface temperature to both juvenile growth and adult surplus energy was quadratic with an optimum value. Recruitment biomass has been a relatively larger component than adult production of total stock growth, particularly during the period of high fishing intensity. This resulted in large fluctuations in stock biomass; in recent years, with lower fishing intensity, adult production has been a larger component of stock growth, and the stock biomass has become more stable.

Patterns and influences on Dolly Varden migratory timing in the Chignik Lakes, Alaska, and comparison of populations throughout the northeastern Pacific and Arctic oceans

2013 ◽  
Vol 70 (5) ◽  
pp. 655-665 ◽  
Author(s):  
Morgan H. Bond ◽  
Thomas P. Quinn
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Environmental Data ◽  
Sea Surface ◽  
Upstream Migration ◽  
Dolly Varden ◽  
Factors Affecting ◽  
Migration Timing ◽  
The North

Dolly Varden (Salvelinus malma) are a facultatively anadromous salmonid common around much of the North Pacific Rim, but little is known about the environmental factors affecting the timing and diversity of their migration. We combined telemetry of anadromous fish with long-term monitoring of Dolly Varden upstream migration timing and environmental data in the Chignik Lakes watershed in Alaska and then compared the timing data with that of other streams where only count data were available. Telemetry revealed two upstream migration modes: midsummer and late fall at the Chignik Lakes. Weir counts indicated that timing fluctuated markedly over the monitoring period (1996–2011) and was negatively correlated with June sea surface temperature. The relationship between sea surface temperature and migration timing in other watersheds with long-term records was as follows: negative (Buskin River), positive (Auke Creek), or nonexistent (Goodnews and Kanektok rivers). Among 18 streams and rivers throughout the eastern Pacific range of Dolly Varden, median upstream migration date increased with latitude. Overall, Dolly Varden migration timing is more variable, protracted, and more strongly influenced by local sea surface temperatures than is typical of semelparous salmonids. These results are likely indicative of other iteroparous salmonids in Pacific waters that share similar environments and life-history characteristics.

Effect of Sea Surface Temperature on The Metal Zn Contents in Inshore and Offshore Water of Blanakan Coast, West Java, Indonesia

2019 ◽  
Author(s):  
Nur Tsalits Fahman Mughni
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Marine Environment ◽  
Sea Surface ◽  
Inshore Water ◽  
Offshore Water ◽  
West Java ◽  
Factors Affecting ◽  
Zn Content ◽  
Positive Effect

The Sea Surface Temperature (SST) is known as one of prominent factors affecting the concentration of metals in the marine environment. Hence, this research is aiming to study the effect of SST on Zn content distribution in the seawater of Blanakan coast. The Zn was measured from sampled seawater collected from 7 stations. Those stations were representing inshore and offshore of Blanakan coast. The sampled water then analyzed by AAS to obtain the Zn contents. The result confirms a positive effect of SST on Zn contents (r2 = 0.18). An increase of SST from 25 to 31 0C was followed by increase of Zn in seawater from 0.31 to 0.50 mg/l of water. Respectively, all Zn values in Blanakan coast have exceeded the permissible limit of EPA (0.09 mg/l for seawater). The effect of SST on the Zn contents is observed in the offshore rather than inshore water of Blanakan coast. This research also presents a 12 month Zn prediction. Following the SST fluctuation, it is predicted that Zn in seawater will be higher in February-May and lower in July-September.

Holocene sea surface temperature variations recorded in corals from Kikai Island, Japan

2017 ◽  
Vol 51 (4) ◽  
pp. e9-e14 ◽  
Author(s):  
Hiroto Kajita ◽  
Atsuko Yamazaki ◽  
Takaaki Watanabe ◽  
Chung-Che Wu ◽  
Chuan-Chou Shen ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Temperature Variations

PENENTUAN DAERAH POTENSIAL BUDIDAYA RUMPUT LAUT KAPPAPHYCUS ALVAREZII DI PROVINSI NUSA TENGGARA TIMUR

2019 ◽  
Vol 3 ◽  
pp. 929
Author(s):  
Marianus Filipe Logo ◽  
N M. R. R. Cahya Perbani ◽  
Bayu Priyono
Keyword(s):  
Dissolved Oxygen ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Kappaphycus Alvarezii ◽  
Sea Surface

Provinsi Nusa Tenggara Timur (NTT) merupakan penghasil rumput laut kappaphycus alvarezii kedua terbesar di Indonesia berdasarkan data Badan Pusat Statistik (2016). Oleh karena itu diperlukan zonasi daerah potensial budidaya rumput laut kappaphycus alvarezii untuk pengembangan lebih lanjut. Penelitian ini bertujuan untuk menentukan daerah yang potensial untuk budidaya rumput laut kappaphycus alvarezii di Provinsi NTT berdasarkan parameter sea surface temperature (SST), salinitas, kedalaman, arus, dissolved oxygen (DO), nitrat, fosfat, klorofil-a, dan muara sungai. Penentuan kesesuaian lokasi budidaya dilakukan dengan memberikan bobot dan skor bagi setiap parameter untuk budidaya rumput laut kappaphycus alvarezii menggunakan sistem informasi geografis melalui overlay peta tematik setiap parameter. Dari penelitian ini diperoleh bahwa kadar nitrat, arus, kedalaman, dan lokasi muara sungai menjadi parameter penentu utama. Jarak maksimum dari bibir pantai adalah sekitar 10 km. Potensial budidaya rumput laut kappaphycus alvarezii ditemukan di Pulau Flores bagian barat, kepulauan di Kabupaten Flores Timur dan Alor, selatan Pulau Sumba, Pulau Rote, dan Teluk Kupang.

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