Artisanal fishing on the Kenya coast: what are the impacts?

Item Type Conference Material

Authors Samoilys, Melita; Osuka, Kennedy; Waweru, George; Obura, David

Download date 01/10/2021 16:37:12

Link to Item http://hdl.handle.net/1834/8850 Artisanal fishing on the Kenya coast: what are the impacts? Melita Samoilys1, Kennedy Osuka1*, George Waweru1 & David Obura1

1. CORDIO East Africa, P.O.BOX 10135, Mombasa 80101, Kenya

* [email protected]

7th WIOMSA Scientific Symposium 24-29th October 2011 Mombasa, Kenya Artisanal fishers Kenyan Coast Introduction 14000

12000

Population on East African 10000 coast >20 million people. 8000 Expected to grow to 39 million 6000

Fisher number Fisher 4000 people by 2014. 2000 Most dependent on marine 0 2004 2006 2008 resources leading to issues of: Years .overfishing Illegal gears (FiD Act) 1200 Beach seine Spear gun .destructive and illegal fishing 1000

Management difficult 800

.Multispecies 600

.Multi gear(14 artisanal gears) 400 Food insecurity gears of Number 200 0 2004 2006 2008 Year Source FiD Frame survey 2004, 2006 & 2008 Hypotheses & rationale Artisanal fishery catch rates are in decline and stocks are overfished Populations of reef fish are declining which reflect the declining trend in fishery catch rates The artisanal gears used have varying destructive aspects which are also difficult to manage Examined whether current government regulations are suitable for the different gears Methods Review of published papers and some unpublished reports on fishing to extract key variables •CPUE - measure of the state of each fishery •Gear catch composition – species contributing 65% - 75% •Fish population abundance - UVC surveys

An 8 year CORDIO dataset (1998-2006) on artisanal fisheries and 2 year UVC estimates in Diani-Chale used to supplement data from the location. Analysis focused on •Commonly reported & used gears: basket traps, gill net, handline, speargun and beach seine •Abundance of seven families (Lutjanidae, Lethrinidae, Seranidae, Haemulidae Acanthuridae, Siganidae, & Scaridae) Study area Study sites grouped into six locations (N to S): Kiunga-Lamu, Malindi-Watamu, Mombasa, Diani - Chale, Gazi, Shimoni Results Data sourced from 25 published & unpublished reports &data a) CPUE trend From 7 studies CPUE declined 4 fold from the mid 1980s (13.7 ±1.6 kg/fisher/trip) average catch rates in 2006 to the 1990s (3.2±0.1 are 23% of what they were in kg/fisher/trip) the mid 1980s Sufficient data for long term CPUE trend analysis were available for 2locations; Mombasa and Diani-Chale. CPUE & Juvenile capture CPUE since 1994 have been stable Catch rates lowest in beach seine highest in spear guns (KW test; p<0.01). Mean % Gear juveniles Juvenile capture Traps 44.9 highest in beach seine & Gill net 49.4 lowest in spear guns Beach seine 68.4 Handline 55.6 Spear gun 38.2 All gears 50.1 b) Catch composition Few species Basket trap Handline dominate the 70 70.0

60 60.0

Lethrinus Lethrinus borbonicus borbonicus 50 catches across all Siganus sutor 50.0

gears except 40 40.0 Lethrinus Lethrinus mahsena

30 30.0 Lethrinus lentjan Leptoscarus vaigiensis

Lethrinus Lethrinus mahsena 20.0

handlines 20 Lethrinus lentjan

Lethrinus Lethrinus miniatus

Lutjanus Lutjanus fulviflamma

Lethrinus Lethrinus xanthochilus Cheilios Cheilios inermis 10 Lethrinus borbonicus 10.0 Primary catches Mean relative abundance (%) 0 0.0 for all gears Beach seine 70 Gill net 70.0 remarkably similar 60 60.0 50  Siganus sutor 50.0 40 Siganus sutor 40.0 (max 44.8%) and Leptoscarus vaigiensis

30 30.0 Unspecified

20 20.0 Leiognathus equula

Lethrinus Lethrinus harak Siganus Siganus sutor

Leptoscarus Lethrinus mahsena

Leptoscarus vaigiensis Acanthurus triostegus 10 Lethrinus mahsena

Mean relative Mean relative abundance (%) 10.0

Unspecified

Lethrinus Lethrinus lentjan Sardinella Sardinella sp. vaigiensis (47.3 %) Lethrinus harak 0 0.0 dominated the catch Species Spear gun

70

60 vaigiensis 50 Leptoscarus

40

30

20 Unspecified Siganus Siganus sutor

10 Calatomus carolinus Mean relative Mean relative abundance % 0 Species c) Changes in catch composition over time Species diversity has i) Basket traps declined over time Relative contribution of S. sutor and L. vaigiensis has increased substantially from 1999 to 2007 ii) Gill net

iii) Beach seines Piscivores Lutjanidae Lethrinidae 200 K-W test H=2.047 200 K-W test H=0.5271 180 p=0.360 180 p=0.768 d)Trends in fish densities 160 160 140 140 120 120 100 100 Population density 80 80 60 60 40 40 data provide an 20 20 Abundance (No./1000 m2) m2) Abundance (No./1000 0 0 independent look at the 1980s 1990s 2000s 1980s 1990s 2000s Haemulidae K-W test H=0.089 Serranidae 10 p=0.766 10 K-W test H=0.0742 status of fish stocks 9 9 p=0.964 8 8 7 7 Fish densities variable 6 6 5 5 4 4 over time. Differences 3 3 2 2

Abundance (No./1000 m2) (No./1000 Abundance 1 1 between years NS for 6 0 0 1980s 1990s 2000s 1980s 1990s 2000s

Herbivores of the 7 families. Acanthuridae 250 K-W test H=12.46 Scaridae K-W test H=1.996 p=0.002 250 p=0.369 80s vs 90s; p=0.005 Some families show 200 80s vs 00s; p=0.004 200 90s vs 00s; p=0.5136 increase from the 1980s 150 150 100 100

to peak in the 1990s and 50 50

Abundance (No./1000 m2) Abundance (No./1000 0 0 1980s 1990s 2000s 1980s 1990s 2000s then decline in the Year period

Siganidae K-W test H=1.724 2000s 250 p=0.423  200 Acanthurids showed a 150 steady decline from the 100 50

0

1980s, (KW test p<0.01) m2) Abundance (No./1000 1980s 1990s 2000s Year period e) Management Effect of management on F6 P4 abundance of fish 1.5 F8 F3 assessed using R3 1 Ac P2R4F5 PCA F4F9 P3 0.5 R2 Management F1 F10 F11 P1 zones: Fished, 0 Si F18 SeHa F15F14 F16F12F17 R1 F7 -0.5 Reserve & Parks P8 F13 P14P15P12P11 F2 P9 P13 Based on KWS -1 P10 enforcement Sc Le -1.5

Component 2(27.72% eigenvalue 13.06) eigenvalue 2(27.72% Component R5 P6 -2 P7 P5 -2.5

-3 Lu -4.8 -4 -3.2 -2.4 -1.6 -0.8 0 0.8 1.6 Component 1(50.25%, eigenvalue 23.67) Summary Protected areas and improved enforcement of fisheries regulation appear to have had positive effects on reef fish stocks Steady CPUE from mid 1990s to 2006 suggests sustainable fishing across common artisanal gears Declines in species diversity in catches are of concern with increasing effort on two key species: S. sutor (rabbit fish), L. vaigiensis (seagrass parrot fish). Species specific management plans might therefore be necessary. Illegal status of spearguns not justified by results – lowest juvenile retention rates and highest CPUE. In contrast beach seine ban well supported by results. Thank you for your attention