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  • 1
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    Fisheries Society of Nigeria | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/23529 | 19325 | 2018-05-09 12:51:48 | 23529 | Fisheries Society of Nigeria
    Publication Date: 2021-07-14
    Description: Information on sex composition of fish/shellfish species is important in determining reproductive potentials and estimating size structure of a given stock. Sustainable fisheries management options and policies usually rely on this aspect of the reproductive biology. In the present study, the sex ratios of three palaemonid shrimps, Macrobrachium macrobrachion, Macrobrachium vollenhovenii and Macrobrachium equidens were studied over an annual cycle with respect to gear type. Male: female relationship for M. macrobrachion caught with beach seine, pushnet and trap were 1:2.2, 1:2.1 and 1:2.15 respectively, while the M:F ratios for M. vollenhovenii were 1:1.27 (beach seine), 1:1.32 (pushnet) and 1:1.64 (trap). The overall M:F ratios during the annual cycle were 1:2.15 (M. macrobrachion), 1:1.47 (M. vollenhovenii), and 1:1.74 (M. equidens). The monthly sex ratios indicated that there were more females than males during the period, except for M. equidens which had a ratio of 1:0.78 in the month of August. This is advantageous for the stock dynamics of the species, especially if the males could mate with more than one female during any reproductive season.
    Description: Includes:- 1 table.;11 refs.
    Keywords: Biology ; Fisheries ; Macrobrachium equidens ; Macrobrachium macrobrachion ; Macrobrachium vollenhovenii ; Nigeria ; Cross River Estuary ; brackishwater environment ; freshwater environment ; Sex ratio ; Shrimp fisheries ; Reproductive cycle ; Population structure
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 694-697
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  • 2
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    Fisheries Society of Nigeria | Lagos
    In:  http://aquaticcommons.org/id/eprint/22995 | 19325 | 2018-03-04 05:33:19 | 22995 | Fisheries Society of Nigeria
    Publication Date: 2021-07-12
    Description: Some aspects of the reproductive biology of the three dominant species in the 〈i〉Macrobrachium〈/i〉, fishery of the Cross River Estuary namely 〈i〉M. macrobrachion, M. vollenhovenii and M. equidens〈/i〉, were studied. Due to the difficulties associated with identifing the onset of maturity of 〈i〉Macrobrachium〈/i〉 males, only the females were used in the study. The size massive maturation (TL〈sub〉m〈/sub〉 in mm) for 〈i〉M. macrobrachion〈/i〉 was 68.83 (CI: 66.63-71.10 mm) at corresponding age of 6.61 (CI: 6.28-6.96) months. TL〈sub〉m〈/sub〉 for 〈i〉M. vollenhovenii〈/i〉 was 106.74 (CI: 102.81. 110.81), at a corresponding age of 7.42 (CI: 7.01-7.82) months, while TL〈sub〉m〈/sub〉 for 〈i〉M. equidens〈/i〉 was 59.09 (CI: 57.50-60.72), at the age of 7.70 (CI: 7.39-8.03) months. Average fecundity for 〈i〉M macrobrachion, M. vollenhovenii and M. equidens〈/i〉 were 2490 (range 270-4710), 23,943 (range 1744-46,141), and 2359 (range 400-4318) eggs per female, respectively. The larger females had more eggs than the smaller ones. Understanding of the reproductive biology of these biological species is indispensable for efficient management of their resources.
    Description: Inludes:- 4 tables.;13 refs.
    Keywords: Biology ; Fisheries ; Macrobrachium macrobrachion ; Macrobrachium vollenhovenii ; Macrobrachium equidens ; Nigeria ; Calabar R. ; brackishwater environment ; Reproductive cycle ; Reproduction ; Shrimp fisheries ; Fecundity ; Sexual maturity
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 144 - 148
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  • 3
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    Fisheries Society of Nigeria | Lagos
    In:  http://aquaticcommons.org/id/eprint/22996 | 19325 | 2018-03-05 09:03:15 | 22996 | Fisheries Society of Nigeria
    Publication Date: 2021-07-12
    Description: The artisanal shrimp fishery of the Cross River Estuary, SE Nigeria is exploited with three main shrimping gears, viz: beach seine, push net and trap. While the beach seine and push net are active gears, the trap is passive. Catch composition from the three gears was analysed for species diversity, catch contribution in weight and sex ratio. The trap showed the lowest species diversity, with only three Macrobrachium (M. macrobrachion, M. vollenhovenii and M. equidens) species represented in the catch, while Callinectes crab and Eleotris were by-catch. The complete absence of Penaeus notialis from trap catches throughout the sampling period of eighteen months was remarkable, while M. equidens was very low in abundance. The beach seine and push net had similar species composition in their catches with more than thirteen shrimp species represented. The catch per unit effort for the three gears varied, with beach seine contributing 46.13%, push net 24.41 % and trap 29.46%, of the overall catch. The sex ratio (male: female) was 1 :2.2 (beach seine), 1 :2.1 (push net), 1:2.15 (trap) for M. macrobrachion, 1 :1.27 (beach seine), 1 :1.32 (push net) and 1 :1.64 (trap), for M. vollenhovenii. The size structure showed more juveniles (below 40 mm) in beach seine and push net. Analysis of catches from the three gears showed some complexities as active and passive gears manifested extreme characteristics in their selection. In managing this fishery, therefore, a middle-of-the road option would be necessary, and we recommend the closed season.
    Description: Includes:- 1 table.;1 fig.;9 refs.
    Keywords: Fisheries ; Nigeria ; Cross River Estuary ; brackishwater environment ; Gear selectivity ; Gear research ; Catch statistics ; Shrimp fisheries ; Catch composition ; Stock assessment ; By catch
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 149 - 152
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  • 4
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24650 | 19325 | 2018-05-26 12:01:47 | 24650 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: The survey was performed in the Calabar Municipality, Calabar South, Odukpani, Akpabio and New Bakassi Local Government Areas. Taken as indicator, number of canoes, the largest villages are situated in Akpabio and New Bakassi LGOs and the smallest in Calabar Municipality and Calabar South. The larger villages base economically apart from fishery on oil palm-dominated agriculture. There are villages where each man is a fisher and also a farmer and others, were these main professions are performed by different persons. In the larger villages, there are traditionally operating carpenters (boats builders), hunters, honey samplers and wood cutters. Nearly all women are engaged in fish trading and several as fish and shrimp processor (smoke-drying) and periwinkle sampler/processor. In the larger villages are three sizes of canoes, small for two, medium for seven and large for 10-15 crew members. The small canoes are mainly used for the gill net fishery system on juvenile bonga (ekpai) in the dry season and on croaker and other demersal and semi-demersal species mainly in the raining season and are common in all surveyed villages. They are also used for fisheries with trap, cast net and long line. With mediu sized canoes, it's mainly operated the anchor net for catch of estuarine shrimp and sometimes boat seine for adult bongo (ibat). The larger canoes are engaged in the purse seine fishery on ibat in the near-coastal waters. In most of the larger villages, it is a common expedition fisheries; fishermen leave for up to several weeks out of their homes and operate in the more productive outer estuary and near-coastal waters, mostly on an estuarine shrimp; they produce smoke-dried products in their camps. The mean catch per boat per day for the small about of 5kg, for the medium-sized 15kg and for the larger purse seine canoes more than 100kg. In Calabar Municipality and South LGAs, all catches are sold fresh in own small markets at the landing site. In other LGAs the catches are processing to smoke-dried product is common. However, by using the mostly existing road connections to Calabar, and also selling of fresh fish is performed. By estimation, the monthly mean income per fisher family in the larger villages is N30, 000, after paying for repairs of nets and outboard engine. On the daily income for fish processing and trading, women included N0-500 and the men, probably by N100 or less.
    Description: Includes: 6 references.
    Keywords: Fisheries ; Nigeria ; Cross River State ; freshwater environment ; automation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 335-337
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  • 5
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    In:  http://aquaticcommons.org/id/eprint/3594 | 424 | 2011-09-29 17:07:52 | 3594 | Fisheries Society of Nigeria
    Publication Date: 2021-06-27
    Description: Monthly catches of the Macrobrachium fisheries were recorded at a commercial shrimp landing site on the coasts of Calabar (Nigeria), from April 1997 to August 1998. Catches fluctuated over an annual cycle, with two peaks occurring from May-July and November-December. These peaks represented periods of major activities, reproduction, recruitment or migration. Also, mean catches decreased in the months of February and August, corresponding to the peak of dry season and the so-called 'August break', respectively. Catches from active gears (seine, push net) varied among the moon phases too, with a main peak during full moon, and the minimum catch was recorded during the first moon quarter. However, the catch from passive gear (trap) depicted an inverse relationship, showing a peak during the first moon quarter. Variation in catches at different months and moon phases were significant at P:0.05. Recognize these variations and trends would help in management decisions such as defining closed seasons without adversely affecting the economy of the fishers
    Keywords: Management ; Fisheries ; Environment ; Nigeria ; Cross River ; Cross Estuary ; catch composition ; catch statistics ; catch/effort ; environmental effects ; fishery management ; fishing gear ; marine crustaceans ; moon phases ; recruitment ; reproductive cycle ; seasonal variations ; shrimp fisheries ; vertical migrations ; Macrobrachium
    Repository Name: AquaDocs
    Type: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 48-52
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