An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria
The environmental conditions of Kainji Lake from 1971/72 to date appear to have stabilized to a large extent, judging from the similarity of physico-chemical parameters investigated in this study over the period. Solar radiation (as reflected in variation in temperature) and pH have remained largely constant over the years, while conductivity (index of nutrient enrichment), though significantly higher in 1995/96, could be described as sporadic and needs further monitoring to ascertain its trend in the lake. While water transparency and dissolved oxygen were higher in 1971/72 compared to the other years, these increases cannot be said to be overwhelming. The lower transparency in 1995/96 was due to the exceptional flood of that year and may have also accounted for the poorer dissolved oxygen concentration compared to the other years due to its impact on photosynthesis. There is no evidence from this study to indicate that primary productivity has increased over the years. Consequently, the observed increase in fish yield by the KLFPP from CAS, which is corroborated by estimates from the MEI, cannot be supported on the basis of improved photosynthetic production. The phenomenal high levels of conductivity recorded during certain periods in 1995 (600 mu mhos cm super(-1)) are hitherto unknown in the lake and may indicate a trend towards nutrient enrichment. However, it is premature at this stage to conclude on its long-term impact on primary production and consequently, on fish yield. Secondly, the notion of overfishing in the 80s (Ita, 1993), may need to be further examined as low or dwindling catches could be due to a number of factors among which are the level of fishing effort, the type and efficiency of gears and the intensity of sampling. It would appear that with the intervention of KLFPP, the better management of the lake's fisheries would increase the current level of catch. It also needs to be examined how much of the clupeid fisheries, which is now known to account for a substantial proportion of the total fish yield in Kainji Lake, was included in the sampling of the 80s. (PDF contains 43 pages)
Main Authors: | , , |
---|---|
Format: | monograph biblioteca |
Language: | English |
Published: |
Nigerian-German (GTZ) Kainji Lake Fisheries Promotion Project
2001
|
Subjects: | Fisheries, Biology, Environment, Nigeria, Lake Kainji, biological production, catch/effort, pelagic environment, population number, primary production, stock assessment, yield, |
Online Access: | http://hdl.handle.net/1834/21527 |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
id |
dig-aquadocs-1834-21527 |
---|---|
record_format |
koha |
spelling |
dig-aquadocs-1834-215272021-06-26T05:55:48Z An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria Adeniji, H.A. Ovie, S.I. Mdaihli, M. Fisheries Biology Environment Nigeria Lake Kainji biological production catch/effort pelagic environment population number primary production stock assessment yield The environmental conditions of Kainji Lake from 1971/72 to date appear to have stabilized to a large extent, judging from the similarity of physico-chemical parameters investigated in this study over the period. Solar radiation (as reflected in variation in temperature) and pH have remained largely constant over the years, while conductivity (index of nutrient enrichment), though significantly higher in 1995/96, could be described as sporadic and needs further monitoring to ascertain its trend in the lake. While water transparency and dissolved oxygen were higher in 1971/72 compared to the other years, these increases cannot be said to be overwhelming. The lower transparency in 1995/96 was due to the exceptional flood of that year and may have also accounted for the poorer dissolved oxygen concentration compared to the other years due to its impact on photosynthesis. There is no evidence from this study to indicate that primary productivity has increased over the years. Consequently, the observed increase in fish yield by the KLFPP from CAS, which is corroborated by estimates from the MEI, cannot be supported on the basis of improved photosynthetic production. The phenomenal high levels of conductivity recorded during certain periods in 1995 (600 mu mhos cm super(-1)) are hitherto unknown in the lake and may indicate a trend towards nutrient enrichment. However, it is premature at this stage to conclude on its long-term impact on primary production and consequently, on fish yield. Secondly, the notion of overfishing in the 80s (Ita, 1993), may need to be further examined as low or dwindling catches could be due to a number of factors among which are the level of fishing effort, the type and efficiency of gears and the intensity of sampling. It would appear that with the intervention of KLFPP, the better management of the lake's fisheries would increase the current level of catch. It also needs to be examined how much of the clupeid fisheries, which is now known to account for a substantial proportion of the total fish yield in Kainji Lake, was included in the sampling of the 80s. (PDF contains 43 pages) Nigerian-German (GTZ) Kainji Lake Fisheries Promotion Project 2021-06-24T15:55:50Z 2021-06-24T15:55:50Z 2001 monograph 978-037-018-8 1119-1449 http://hdl.handle.net/1834/21527 en Nigerian-German Kainji Lake Fisheries Promotion Project Technical Report Series application/pdf application/pdf Nigerian-German (GTZ) Kainji Lake Fisheries Promotion Project New Bussa, Nigeria http://aquaticcommons.org/id/eprint/3857 424 2011-09-29 16:45:34 3857 Deutsche Gesellschaft für Technische Zusammenarbeit (Nigeria Office) |
institution |
UNESCO |
collection |
DSpace |
country |
Francia |
countrycode |
FR |
component |
Bibliográfico |
access |
En linea |
databasecode |
dig-aquadocs |
tag |
biblioteca |
region |
Europa del Oeste |
libraryname |
Repositorio AQUADOCS |
language |
English |
topic |
Fisheries Biology Environment Nigeria Lake Kainji biological production catch/effort pelagic environment population number primary production stock assessment yield Fisheries Biology Environment Nigeria Lake Kainji biological production catch/effort pelagic environment population number primary production stock assessment yield |
spellingShingle |
Fisheries Biology Environment Nigeria Lake Kainji biological production catch/effort pelagic environment population number primary production stock assessment yield Fisheries Biology Environment Nigeria Lake Kainji biological production catch/effort pelagic environment population number primary production stock assessment yield Adeniji, H.A. Ovie, S.I. Mdaihli, M. An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria |
description |
The environmental conditions of Kainji Lake from 1971/72 to date appear to have stabilized to a large extent, judging from the similarity of physico-chemical parameters investigated in this study over the period. Solar radiation (as reflected in variation in temperature) and pH have remained largely constant over the years, while conductivity (index of nutrient enrichment), though significantly higher in 1995/96, could be described as sporadic and needs further monitoring to ascertain its trend in the lake. While water transparency and dissolved oxygen were higher in 1971/72 compared to the other years, these increases cannot be said to be overwhelming. The lower transparency in 1995/96 was due to the exceptional flood of that year and may have also accounted for the poorer dissolved oxygen concentration compared to the other years due to its impact on photosynthesis. There is no evidence from this study to indicate that primary productivity has increased over the years. Consequently, the observed increase in fish yield by the KLFPP from CAS, which is corroborated by estimates from the MEI, cannot be supported on the basis of improved photosynthetic production. The phenomenal high levels of conductivity recorded during certain periods in 1995 (600 mu mhos cm super(-1)) are hitherto unknown in the lake and may indicate a trend towards nutrient enrichment. However, it is premature at this stage to conclude on its long-term impact on primary production and consequently, on fish yield. Secondly, the notion of overfishing in the 80s (Ita, 1993), may need to be further examined as low or dwindling catches could be due to a number of factors among which are the level of fishing effort, the type and efficiency of gears and the intensity of sampling. It would appear that with the intervention of KLFPP, the better management of the lake's fisheries would increase the current level of catch. It also needs to be examined how much of the clupeid fisheries, which is now known to account for a substantial proportion of the total fish yield in Kainji Lake, was included in the sampling of the 80s. (PDF contains 43 pages) |
format |
monograph |
topic_facet |
Fisheries Biology Environment Nigeria Lake Kainji biological production catch/effort pelagic environment population number primary production stock assessment yield |
author |
Adeniji, H.A. Ovie, S.I. Mdaihli, M. |
author_facet |
Adeniji, H.A. Ovie, S.I. Mdaihli, M. |
author_sort |
Adeniji, H.A. |
title |
An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria |
title_short |
An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria |
title_full |
An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria |
title_fullStr |
An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria |
title_full_unstemmed |
An evaluation of the pelagic primary productivity and potential fish yield of Kainji Lake, Nigeria |
title_sort |
evaluation of the pelagic primary productivity and potential fish yield of kainji lake, nigeria |
publisher |
Nigerian-German (GTZ) Kainji Lake Fisheries Promotion Project |
publishDate |
2001 |
url |
http://hdl.handle.net/1834/21527 |
work_keys_str_mv |
AT adenijiha anevaluationofthepelagicprimaryproductivityandpotentialfishyieldofkainjilakenigeria AT oviesi anevaluationofthepelagicprimaryproductivityandpotentialfishyieldofkainjilakenigeria AT mdaihlim anevaluationofthepelagicprimaryproductivityandpotentialfishyieldofkainjilakenigeria AT adenijiha evaluationofthepelagicprimaryproductivityandpotentialfishyieldofkainjilakenigeria AT oviesi evaluationofthepelagicprimaryproductivityandpotentialfishyieldofkainjilakenigeria AT mdaihlim evaluationofthepelagicprimaryproductivityandpotentialfishyieldofkainjilakenigeria |
_version_ |
1756077509392203776 |