Seasonal variation of Primary productivity and Small Pelagic Fish Catches along the western Coast of Pemba Island.
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Date
2020
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Dar es salaam
Abstract
Seasonal variation of Primary productivity and Small Pelagic Fish Catches along the western Coast of Pemba Island.
Hellen Joseph Kizenga
Master of Science in Marine Science
University of Dar es salaam, Institute of Marine Science, 2020.
Understanding the relationship between phytoplankton and fisheries productivity is very crucial in identifying potential areas for fishing. This study aimed at determining the seasonal variation of primary productivity and small pelagic fish catches along the Western coast of Pemba Island waters. The data used for this study included: (a) Remotely- Sensed Data-Chlorophyll-a (Chl-a) and Sea Surface Temperature (SST) (b) in-situ measured data- Dissolved Oxygen (DO) Total Suspended solids (TSS), pH, Salinity, SST, Phosphates and nitrates (c) the small pelagic fish catch (landings ) data, and (d) qualitative information- Key Informant Interview (KII) and Nominal Group Technique (NGT). The satellite derived measurements along with the fish catch data were collected over an extended period of 8 years (2011-2018). The in-situ measured data were acquired on seasonal basis that is, the Northeast (NE) and Southeast (SE) monsoon season for duration of 2 weeks during each season. The results showed that both the in-situ and satellite Chl-measurements were higher during the (SE) Monsoon than during the NE monsoon season. Similarly, DO,TSS, phosphates and pH were significantly higher during the SE MONSOON season. In contrast, SST, salinity and nitrates were significantly higher during the NE Monsoon season than during the SE Monsoon season. Chl-a and SST showed a strong negative correlation (R=-07, P<0.05). The results of the analyses of the relationship between fish catches and environmental parameters revealed that sardines and mackerel were significantly positively correlated with Chl-a at a 1-month lag (RIIag = 0.7, p<0.05) =08, p<0.05), respectively. Furthermore, anchovies displayed a strong correlation with Chl-a at 4-months’ time lag (R4lag =0.8, p<0.05). From the presented results, it was concluded that the relationship between small pelagic fish catches and environmental parameters (Chl-a and SST) was species dependent. The catches of common small pelagic fish groups such as mackerel and sardines were favored by the abundance of phytoplankton productivity. Anchovies were the exceptions. This would therefore call for different management strategies for the two categories of pelagic fish.
Description
Available in print form, East Africana collection, Dr. Wilbert Chagula Library, class mark (THS EAF QK934.T34K594)
Keywords
Fishes,, Seasonal variation,, Western coast,, Pemba Island,, Marine phytoplankton
Citation
Kizenga, H. J(2020)Seasonal variation of Primary productivity and Small Pelagic Fish Catches along the western Coast of Pemba IslandMasters Dissertation,University of Dar es Salaam, Dar es Salaam.,