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African Journal of Aquatic Science Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/taas20 An assessment of a light-attraction fishery in southern Lake Malawi OLF Weyl , J Kazembe , AJ Booth & DS Mandere Published online: 07 Jan 2010.

To cite this article: OLF Weyl , J Kazembe , AJ Booth & DS Mandere (2004) An assessment of a light-attraction fishery in southern Lake Malawi, African Journal of Aquatic Science, 29:1, 1-11, DOI: 10.2989/16085910409503787

To link to this article: http://dx.doi.org/10.2989/16085910409503787

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This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 A llison 1997, Turner Turner 1997, llison A and (Tweddle annum per tons 000 ponents 30 com c. yield all-scale sm fisheries and these large-scale both includes t tha that the fishery targeted juveniles in stratum 2.1, while in stratum 3.1 most individuals were harvested after reaching their length- length- their reaching after harvested were individuals most 3.1 stratum in while 2.1, stratum in juveniles targeted fishery the that this study. Catch per unit effort in stratum 2.1 was generally lower than that recorded in stratum 3.1 but nets in stratum 2.1 fished fished 2.1 stratum in nets but 3.1 stratum in recorded that than lower generally was 2.1 stratum in effort unit per Catch study. this Malawi Lake southern in fishery light-attraction a of assessment An ). 1 0 0 2 only viable management options, until such time as additional biological and fisheries data are available for the application of stock stock the of be may application the closure for area or available are data ­ itation lim fish fisheries this effort and for biological assemblage, interventions Comparisons species additional strata. as management time diverse both a that such showed in until targets models. indicates catch 85% area the in of on fishery options, assessment species the excess target Since in management size-selection ajor and m of viable was only position area-specific. catch be to distributions annual catch-com need of the ery to dependence Length-frequency The area. on at-maturity. contribution dependent was combined position Their catch-com that stratum. showed either in catch al A frican Journal o f A quatic S cience 2004, 29(1): 1-11 C opyright © N IS C P ty Ltd ty P C IS N © opyright C 1-11 29(1): 2004, cience S quatic f A o Journal frican A era, and 13 species from nine non-cichlid genera, were identified from the samples. Of the 37 genera identified, only five; five; only identified, genera 37 the Of samples. the from identified gen­ net-1 were cichlid tons 28 from 15.9-23.5) genera, = (CI 19.4 species 62 as of total non-cichlid A estimated was nine respectively. catch 3.1 from Annual stratum in strata. year-1 o net-1 species tw the 13tons in 19.5-28.1) and = (CI catches 23.5 era, and annual 2.1 ilar sim stratum r-1in to yea leading frequently, more Malawi Bay, onkey M 27, ox B PO Fisheries, f o ent epartm D Unit, Research 2Fisheries This study provides the first quantitative assessment of the light-attraction component o f a small-scale purse seine, locally known known locally seine, purse small-scale a f o component light-attraction the of assessment quantitative first a the as provides study This offshore species is ham pered by the ir dispersed nature nature dispersed ir the by 1995). pered pson ham Thom is and enz (M species offshore (Allison sidered unexploited or only lightly exploited (Thom pson and and pson (Thom exploited lightly only or unexploited sidered Bulirani 1995, 1994, (Turner (Banda catch the of 90% than more land traps and fishery a by exploited are fish (Allison The 1995). (Turner species Keywords: Keywords: into a number o f statistical strata. Two strata (‘2.1’ in the southeast arm and ‘3.1’ in the southwest arm of the lake) were selected for for selected were lake) the of arm southwest the in ‘3.1’ and arm southeast the in (‘2.1’ strata Two strata. statistical f o number a into Booth AJ Kazembe2, JWeyl1*, OLF inshore to unexploited pelagic species is a high priority priority high a is species overexploited from pelagic effort fishing unexploited to redirect that inshore fisheries ing many of which have declined as a result of over-fishing over-fishing of result a as declined have which of many handlines longlines, nets, utilising gill fishers seines, all-scale Sm pelagic 2001). seines, beach Ngochera 1989, agasa M a fish by ic supports endem 500 lake bordered than more The Valley with Rift bique. ater ozam ichthyofauna M freshw 2 African diverse and 800km East highly 28 a Tanzania the is in ) 'S Malawi, 0 °3 4 -1 located 'S 0 (9°3 lake Malawi Lake Introduction oaihoi, iiicrms Egalcpi, Oreochromis Engraulicypris, Dimidiochromis, Copadichromis, Received 11 Septem ber 2003, accepted in revised form 1 D ecem ber 2003 ber ecem D 1 form revised in accepted 2003, ber Septem 11 Received n otat te fsoe ih tcs fLk Mlw ae con­ are Malawi Lake of stocks fish offshore the contrast, In 1 D epartm ent o f Ichthyology and Fisheries Science, R hodes University, PO B ox 94, G raham stown 6140, South Africa South 6140, stown raham G 94, ru.ac.za ox B o.weyl@ PO ail: e-m University, author hodes R orresponding Science, C * Fisheries and Ichthyology f o ent epartm 1 D itdi SuhAfrica A South in rinted P These fisheries target predom inantly inshore species, species, inshore inantly predom target fisheries These chilimira t al. et t al. et chilimira net, fishery in two areas o f southern Lake Malawi. For m onitoring purposes the shoreline of Lake Malawi is divided divided is Malawi Lake of shoreline the purposes onitoring m For Malawi. Lake southern f o areas two in fishery net, 2002). However, the econom ic exploitation of of exploitation ic econom the However, 2002). 2002). In the M alawian section of the lake, lake, the of section alawian M the In 2002). — net, CPUE, length-frequency, species composition species length-frequency, CPUE, net, A ll rights reserved rights ll A t al. et 00. o hs esn develop­ reason, this For 2000). et al. et

1999, Allison Allison 1999, 1 n D Mandere DS and et al. et 2002). 2002). t al. et 2 and and Rhamphochromis, h dgu cne i eupe wt bten n ad three and one between with equipped is canoes dugout the 1971, (Balon fisheries African in applied only m com is tion 20 00), or at night with the aid of light-attraction, when the the when light-attraction, of aid the with night at or 00), 20 C oulter 1976, Van Zwieten Zwieten Van 1976, oulter C uot aos n oe agr ln ba. h pak ot is boat plank The boat. plank larger one Malawi and Lake On canoes 1993). dugout FAO 1971, typical ensky a Znam and (Coulter sometimes is cod-end of The 25mm. to mm 6 from ranging size 1998). Smith 1993, (FAO cyprinid ed 'sardine-like' small ira chilim ly transports the dugout canoes to the fishing grounds. One of of One grounds. general­ fishing the which to canoes (9-15hp), dugout otor m the outboard transports ly small a by powered mesh (Weyl with netting netting mosquito ent with ultifilam m lined 36-ply of constructed ically Jackson 1998, ith (Sm outcrops rocky genus erged subm the of near a is cichlids the as currently pelagic known gear light-attraction, locally using all-scale seine sm species, purse only offshore pelagic the harvest Malawi to used Lake On rate. chilimira The The C oncentrating dispersed pelagic fishes using light-attrac- light-attrac- using fishes pelagic dispersed oncentrating C chilimira net is fished either, during the day when semi- semi- when day the during either, fished is net chilimira nets at night using light attraction is well-described well-described is attraction light using night at nets net has a headline length of 70m and is typ­ is and 70m of length headline a has net contributed more than 5% to the total annu­ total the to 5% than more contributed crew com prises nine members using two two using members nine prises com crew

et al. et galcpi sardella ngraulicypris E pdcrmis opadichrom C 2002) to increase the catch catch the increase to 2002) t al. et AFRICAN JOURNAL OF JOURNAL AFRICAN 2000). The operation operation The 2000). AQUATIC SCIENCE AQUATIC SSN 1085 4 1 8-59 160 N S IS hlmira chilim are targeted targeted are is target­ is net. The The net. Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 sen hr o h suhr pr o h SA(iue ) In 1). (Figure SEA the of part southern the of shore estern w focussed study This 2001). gochera (N the lake s; arm the o tw from into taken splits i alaw M Lake end southern its t A and (Coulter sphere quarter a of shape the on takes net the The ves­ summoned. are sta­ remaining is the vessels from lamps away paraffin member, crew pressurised one the with with tioned, canoe dugout the tion com ponent of the the of ponent com tion eyl (W catches nocturnal and diurnal both of ent aggregates epartm tem D alawi (M lake the of section alawian M the moon full uring D storms. by curtailed be may and eather w Znam ensky 1971). The canoe with the lamps is then rowed rowed then is lamps the with canoe The 1971). ensky Znam 2 The fishing periods are, however, highly dependent on on dependent highly however, are, periods fishing The prtr o te o lto o ihn tis To taa (2.1 strata study. Two this trips. for fishing selected of ere w pletion 3.1) ithin com land­ W and the on 1993). ell-defined w of (FAO ber operators of num a ber are 'strata', num a there ed into strata term purpos­ these divided here of is each onitoring areas, m Malawi For Lake of lake. statistical the yield of shoreline fish the the section es of 60% southern c. this on produce ether tog which (SEA), arm area Study is net the and together come The it. boat with fish plank attracted and the canoe drawing net, other the sinking, towards On slowly fish. dugout attracted second the the around and boat i-circle sem plank a in fishing the the canoe from attracted is ultaneously fish sim of quantity sufficient a After sels. size selectivity of the gear. These factors are vital for the der­ the for vital are factors These gear. the of of selectivity size position com species considerable a that hypothesised of and ount ents am assessm catch the from catches al. from landings annual the of rapidly 50% than expanded more fishery for the 500 2 accounted than then, iso­ more to 1999 Since in and and 1961). alawi M the Lake to (Howard northern confined of as w use its shorelines 1960s rocky the in steep, and 2000) (Jackson is catch The 08h00. and 04h00 between end and (16h00) fte moon. the of ing sites at which fish catches are landed by sm all-scale all-scale sm by landed are catches fish which at sites ing Malawi. unrecorded. been boat. plank the into hand by hauled grounds, fishing the reaching On lamps. paraffin pressurised represents the first specific assessm ent of the light-attrac- light-attrac- the of ent study this assessm and fishery specific the first for the advice ent represents anagem m of ivation sys­ onitoring m this 1993), (FAO 1976 since onitored m been statistics). fisheries unpublished Fisheries lake the of s arm est southw and southeast the in areas lated periods buyers. to auctioned and sites landing ell-defined w at landed 1 210km 2 southw est arm (SW A) and the 1 820km 2 southeast 2southeast 820km 1 the and A) (SW arm est 2southw 210km 1 Methods 1999). Lewis and Tweddle (1990) showed that night night that showed (1990) Tweddle and Lewis 1999). W hile catch and effort in the the in effort and catch hile W There is a general lack of published inform ation on the the on ation inform published of lack general a is There The The Stratum 2.1 is situated south of Boadzulu Island, on the the on Island, Boadzulu of south situated is 2.1 Stratum M ost fishing trips com m ence in the late afternoon afternoon late the in ence m com trips fishing ost M hlmira chilim

hlmira chilim . sardella E. nets fish for limited periods before the rise rise the before periods limited for fish nets net w as developed on Lake Malawi Malawi Lake on developed as w net hlmira chilim captured by this fishery may have have may fishery this by captured hlmira chilim hlmira chilim ihr r udrersne in underrepresented ere w fishery hlmira chilim chilimira net fishery in southern Lake Lake southern in fishery net catches, as well as on the the on as well as catches, hlmira chilim nets (W eyl eyl (W nets net is then deployed deployed then is net net fishery has has fishery net et al. et 2000) 2000) et

the catch, were collected by Malawi Departm ent of Fisheries Fisheries of ent Departm Malawi by collected were catch, the at deep m 2 c. from gently slopes bottom lake the area this apig procedure Sampling waters offshore deeper the fish vil­ generally adjacent villages two at these from recorded ere w these of Eighty-two 2002). and Kela sites, landing adjacent o tw at landed ere w 62 nmeaosa he ece, hpk, no ead Kela and be angom M Chipoka, beaches, three at erators enum bi­ a catch, ulti-species m the of nature diverse highly the and lear acC M Cape the of islands the around depth) in (>50m 142 of total a shallow, 2001, In relatively is the In swamps. lake 100m. ira the e extensive chilim 3.1, som is A passing SW stratum 50m rocky of encom the of part and exceeding depth steep depths um is southern to A axim m rapidly SW the the slopes of and bottom coast lake the and northeast nets The these for SWA. ground fishing main The 1). (Figure Chipoka (Turner content mud bottom lake high a and 94 with shoreline sandy, The inantly Island. predom are Boadzulu near 50m att apoc wa ae i ti assment. assessm this in taken conditions as w eather w approach to partite fishery the of susceptibility the to Due 1). operating (Figure nets peninsula The 1). (Figure be Chem and Msaka lages, 1). (Figure Island Boadzulu of south is c. of um axim m a to River Shire pper U the into outflow its 1996). A m onitoring survey conducted in 2001 enum erated erated enum 2001 in conducted survey onitoring m A 1996). otws r, S = pe hr River Shire Upper = USR arm, southwest ac 20 ad eray 01 SA suhat r, W = SWA arm, southeast = SEA 2001. February between and collected 2000 were sites March samples landing catch the where 3.1 showing and 2.1 Malawi Lake strata in southern of Map 1: Figure hlmira chilim Stratum 3.1 is situated on the eastern shoreline of the the of shoreline eastern the on situated is 3.1 Stratum is, ac ad fot aa ageae fr l seis in species all for aggregated data, effort and catch First, nets w ere enum erated in the stratum (W eyl eyl (W stratum the in erated enum ere w nets nets in this stratum (W eyl eyl (W stratum this in nets el Kzme Bohad Mandere and Booth Kazembe, Weyl, et al. et 2002). O f these, these, f O 2002). t al. et

Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 the sub-sam ple w ere identified to genus or species level and and level species or genus to - identified m -sa ere b w su ple A trip. sub-sam fishing the the of pletion com the at ­ sam eighed w as w during three-day the month month, per each days ithin W period. length- consecutive pling and three sam for the species- the sampled of as w ination determ the for used 2.1 as w stratum in pled sam ere w catches 320 and 217 of total random a day, pling sam nets particular the f a O on recorded. ere fishing w ere fishing, w t actively tha nets those of tion 1-11 29: 2004, Science of Aquatic Journal African iidjvnl ccld. u o ifclis nte cuae iden­ accurate the the in of difficulties juveniles of to Due tification cichlid'. juvenile tified undescribed an as categorised iden­ be as w could it but level name al genus inform to an lacked tified species a If tion. to determ ine catch per unit effort (CPUE). Since all all Since (CPUE). effort unit per catch ine determ to frequency com position of their catches. Each landing site site landing Each catches. their of position com frequency The procedures outlined by P ollock ollock P by outlined procedures The each com ponent w as w eighed to the nearest gram and and gram nearest the to eighed w as w ponent com each A 3.1. stratum collected in respectively. days ere 3.1, w 108 and on data and effort 2.1 and stratum in Catch days 77 these on of position. com catch total The species ent. assessm for chosen as propor­ w ple the sam with together site, landing 2001. particular each February at in ent ending and 2000 March in encing m com analysis and mean CPU E for each net fished in period as: the period in in used calculated fished net ere then w as each w s for study E All this CPU stratum basis. mean during trip' and per net collected 'per analysis a on ples sam catch standardised ere w units effort 'uniden­ category the to be not assigned could as w it TL, m species <40m cichlid a cichlids If genus. that within species were names al ine form the haplochrom study this In undescribed Malawi. the of Lake of any m for genera names species (Turner (Turner lack of form al descriptions for m any of the species (Turner (Turner species the the and of any m diversity for high the by descriptions al form plicated of com lack are millimetre. Malawi nearest the Lake to (TL) length total in for fish All easured m taken. as w nets net selected t tha the of from catch catch total the the of land­ ple and nets of selected ple sam as w site random A each ised. at ing random as w period pling 1)), (Figure 3.1 stratum in saka M and 2.1 stratum in Kela of irrespective kilogram, nearest the to eighed w as w nets tekwe, M period the be, Chem within ­ randomised sam the beaches, were Both 1). site r u (Figure landing fo 3.1 and day stratum in and pling Msaka and 2.1, Kasankha stratum in recorded only on the com pletion of the fishing trip, daily daily trip, fishing the was of catch total pletion com their the and on only construction in ilar recorded sim ere w nets juvenile e som with case the as w as level, genus to identified species descrip­ al al inform form a lacking Turner's species any to hereas w assigned as w possible, name hen w used Catch rate Catch lumped. 1996). Turner (1996) lists fairly w ell-established informal informal ell-established w fairly lists (1996) Turner 1996). ------Species identifications of the haplochrom ine cichlids of of cichlids ine haplochrom the of identifications Species (i.e. area each in site landing active ost m the Second, P p(g e- ti-) _ V _ = trip-1) net-1 Eps(kg CPU of ber num the day pling sam each On t al. et 1 1989), all species within this group were were group this within species all 1989), ecrmi ‘ yasalapia’ ‘N is reochrom O Ep n n t al. et " C,.Bs(kg) hlmira chilim (1994) w ere used used ere w (1994) s(trip) Euto 1) (Equation es pres­ nets hlmira chilim group group p and and

w inds that may reach force eight on the Beaufort Scale and and Scale Beaufort the on south-easterly by eight force reach characterised may that August, to inds w May from inter w obtain to here w Total catch for each net during period period during net each for catch Total to contrast in effort, fishing onthly bi-m mean ine determ To Effort ­ tem air average daily a with ber ovem N to ber eptem S from dry ry a brua ry-Fe seasons; ua main Jan the to and 2000 correspond r be periods cem e These er-D b 2001. vem o N 2000; Estimating variance Estimating calculated from the mean proportion of nets from a landing landing a from nets (pfp as: of s) day any proportion on mean fishing the site from calculated 1993). (FAO 25°C of peratures tem air daily average (E quation 2) w as sim ilarly estim ated, and total catch catch total and effort esti­ all For Mean ated, two. the estim of sample. product ilarly the as sim the calculated as 3) w from 2) (Equation ent replacem quation (E with pseudo-values, the drawn of with drawn average ere the w (x,) ber CPUE num of large case a pseudo-values of period, case) pling sam this in each 000 For (1 variability. catch n ttl nul ac fr ah e pr tau o sx bi­ six for stratum per net each for catch annual total and as: culated (FAO procedure onitoring m fisheries standard a effort, daily er m sum dry a ; °C -22 20 of peratures tem air daily average 2000; pril -A arch M periods: onthly bim six for separately ed nhy eid as: periods onthly m period month was was level test confidence pairwise 95% A Dunn's tests. all in parisons. The com used test. multiple for allis used Kruskal-W from and etric m inds w season northerly rainy by a and characterised 28°C; April, to ber ately ovem N late approxim of perature er ctob r-O be tem ep S 2000; st u g u ly-A Ju 2000; ne ay-Ju M ae, h bosrp s odtoe o smpe ie i.e., size, ple sam on conditioned as w bootstrap the mates, of set the in random any ple, of exam For average data. the be observed the from ent replacem Tibshirani and (Efron pling resam bootstrap etric on-param N and s, stratum in 1986) w as conducted to estim ate CPUE, effort and total total and effort CPUE, ate estim to conducted as w 1986) Total catch Total two- a during s stratum in effort Fishing utilised. as w 1993) C(os = TCps(tons) V = ACs(tons) TC„ Ep non-para- a with pared com ere w data CPUE onthly Bi-m calculat­ as w CPUE variations, seasonal marked to Due s(net-1 trips) = 60(days) x x 60(days) = trips) s(net-1 . s C. stn) = s(tons) Ci Ci p s. is the the is p p , com prising 60 possible fishing days, was was days, fishing possible 60 prising com , = 1 = C PU Ep s(kg net-1 trip-1) x x trip-1) net-1 Ep s(kg PU C , E,p s i th catch of of th catch the effort (equal to one trip) expended expended trip) one to (equal effort the n sam pled during the pth period pth period the during pled sam pf^ 1000 s nttis day-1) trips s(net p in stratum s w as cal­ as w s stratum in C.ps /E,ps C.ps E (e trips) s(net Euto 2) (Equation Euto 3) (Equation estim ates ates estim X, would would 3 Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 than that in stratum 2.1 during the periods March/April, March/April, periods the during 2.1 stratum in that than 60 to net-1. decreased 9)kg it -10 (78 hereafter 94 w to ber, increased ber/Decem Novem CPUE in trip-1 July/August fter A sample. the of mass the to to ptotically asym converge would x# 000), 1 the In case pseudo-values. this the of mean etic arithm x#the is here w as same the as w sample. the in pseudo-values values of ber pled num resam the of ber num the the sorted X values w ere chosen to represent the upper and and upper the represent to chosen ere w values X sorted the 4 January/February but w as significantly higher during all all during higher and significantly as w arch/April M stratum in but during 3.1 effort in stratum onthly in Bi-m trips that January/February ) to 6 2B). ilar -1 (3 sim as (Figure w nine 2.1 to arch/April M January/February in trips ) 4 -4 1 (3 38 from January/February. and ctober ber/O eptem S July/August, CPUE, lowest The ctober. ber/O Septem in trip-1 net-1 234)kg h cth o oiin t eu/pce lvl a deter­ was level genus/species at position com catch The te periods. other decreased to effort arch/April onthly M bi-m in 2.1 3.1, trips ) stratum stratum In -51 In 1 (1 trips. 31 strata. ) 9 -5 1 both (5 between in 55 periods fluctuated effort between higher significantly significantly as w May/June 3.1 during stratum in recorded 187 CPUE was (156, trip-1, of 2A). 195 net-1 and (Figure peaks 0)kg -12 In with arch/April, (70 M 93 2A). widely, during trip-1 (Figure net-1 fluctuated 9)kg 1 -2 0 CPUE 6 (1 January/February 3.1 in trip-1 stratum net-1 )kg -69 during (51 trip-1 net-1 6)kg -17 6 7 = CIs (95% 124 from cantly ­ sam all of mass the by catches all in species/genus the of period each during x of ples resam of ber num large a after example, CPUE Species composition Species from quartiles 97.5% and 2.5% the here w intervals, dence yJn ad hn nrae sedl o 6 36- rp in trips ) 4 -5 6 (3 46 to steadily increased then and ay/June M M arch/April to a July/August low of 38 (30 -47 )kg net-1 trip-1. trip-1. net-1 )kg -47 signifi­ (30 38 of in low decreased E illustrated July/August CPU a to are mean 3.1 arch/April M 2.1 and 2.1 stratum In strata 2A. in Es Figure CPU onthly Bi-m Catch ­ sum by Results in species/genus catch each of periods. total all the catch by over ming annual position com and p, period proportional the ultiplying m catches. pled ple subsam each in species the of mass the raising by mined 1. Equation low er 95% confidence intervals respectively (Buckland (Buckland respectively intervals confidence 95% er low 1984). ainewa hn si td by: ated estim then as w Variance The total catch of each species/genus was calculated by by calculated was species/genus each of catch total The confi­ 95% ate estim to used as w ethod m percentile The imotl si ts ftettl ac prnt n stratum in net per catch total the of ates estim onthly Bi-m differed Effort 2B. Figure in shown is effort onthly Bi-m species/genus any for position com species Proportional a x = 00 0 )0 1 = (x) Var

p w as then obtained by dividing the mass mass the dividing by obtained then as w 2 i 1000 = 1 =

[ x - x]2 - x [ i (in (in the 37 ge ne ra id en tified, on ly five; five; ly on tified, en id ra ne ge 37 the 3.1. tum species 13 and genera, cichlid 28 from species 62 of total A rm srtm . ad 5 pce r rcre ol i stra­ in only recorded ere w species 15 and 2.1 stratum from ­ sam the from identified ere w genera, non-cichlid nine from in net-1 tons ) .8 -5 .0 (4 4.9 to ugust July/A esti­ the 2.1, period stratum the In for 2C. Figure in shown are 3.1 and 2.1 genus level in the tw o strata is sum m arised in Table 2. O f f O 2. Table in arised m sum is strata o tw the in level were genus species 36 these, f O catch­ 3.1. from stratum species 51 in and 2.1 pled sam stratum in es pled sam catches 23.5 and 19.4 2.1 ilar; sim respectively. stratum 3.1, ere w in stratum in strata year-1 year-1 net-1 Annual o net-1 tw tons ) .1 8 -2 the .5 tons (19 January/February. for ) .5 3 during -2 .9 ates (15 net-1 estim tons ) catch .7 -9 .1 (5 7.2 N ovem ber/D ecem ber. In stratum 3.1, bi-m onthly catch to catch July/August onthly bi-m during net-1 3.1, tons ) .5 -1 .3 stratum (0 0.8 In from net-1 tons ber. ranged ) .6 ecem -2 .7 ber/D (1 2.1 ovem N from ranged catch onthly bi-m mated recorded from both strata, 24 species w ere recorded only only recorded ere w species 24 strata, both from from identified recorded ere w species different Sixty 1). (Table ples composition Catch 01 n taa . ad . i suhr Lk Malawi Lake February southern to in 3.1 2000 and March 2.1 strata in from 2001 periods bimonthly six during fishery proportional fishing days and (c) catch per net in the the in net per catch (c) and days by fishing represented effort, proportional (b) (CPUE), effort unit per Catch (a) 2: Figure The bi-m onthly and annualised catch com position at at position com catch annualised and onthly bi-m The Apr. Jun. Aug. Oct. Dec. Feb. Feb. Dec. Oct. Aug. Jun. Apr. BIMONTHLY PERIOD BIMONTHLY el Kzme Bohad Mandere and Booth Kazembe, Weyl, chr is m ro h ic d a p o C chilimira net , Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 to m ore than 10% during N o ve m b e r/D e ce m b e r and The genus genus The and of r e b m ce e excess r/D e in b m ve o N contributing during species each 10% with than position, com ore m to strata both in 85% of excess in as w catch annual the to Dimidiochromis kiwinge Dimidiochromis Aulonocara macrochir Aulonocara Aulonocara Aulonocara mentale Alticorpus 1-11 29: 2004, Science of Aquatic Journal African 01 Sprcittx eoe hte seiswsrcre rm tau 21 a,31 b o rm ohsrt (ab) strata both from or (b) 3.1 (a), 2.1 stratum from recorded was species a whether denotes text Superscript 2001. from sampled taxa all of List 1: Table uyAuut n moe hn 0 uig e r t rltvl lre otiuin o h ttl ac, hs genus this catch, total the to contribution large relatively its er/ b vem o N species, during 40% than genus ore m the 3.1, and stratum In ugust 3a). July/A (Figure January/February .ab p sp Bathyclarias ab meridionalis Bagrus ab anguilloides Mormyrus ab microlepis Opsaridium ab microcephalum Opsaridium b b cylindricus mesops b Labeo Labeo litamba Barbus ab eurystomus Barbus johnstoniab Barbus a placodon Trematocranus b eucinostomus Nyassachromis ab a argyrosoma microstoma Trematocranus Nyassachromis b venustus Nimbochromis livingstoniib Nimbochromis chrysogastera Naevochromis ab parvidens Lethrinops a longipinnis Lethrinops b longimanus Lethrinops a lethrinus Lethrinops auritus Lethrinops a alta Lethrinops ab insignis Hemitaeniochromis ab rostratus Fossochromis ab limnothrissa Diplotaxodon greenwoodiab Diplotaxodon b bigeye Diplotaxodon ab argenteus Diplotaxodon Buccochromis rhoadesi Buccochromis nototaenia Buccochromis lepturus Buccochromis atritaeniatus Buccochromis (Table 2). 40% to the total total the considerably to varied 40% position com catch the to species this 2). (Table respectively 3.1 and 2.1 strata in catch annual catch, catch total In the to genus respectively. this 3.1, of and 2.1 contribution the strata these, .1, in 2 stratum assessed catches all is m contribution ro ch o bined re O com 2). heir T (Table . stratum ris, either in licyp u ra g catch n E annual is, phochrom ham is, R m ro ch io id im D otiue ls ta 5 uig rhArl Ma/ue n h ana cth n taa . ad . rsetvl. Despite respectively. 3.1 and 2.1 strata in catch annual the and ay/June M arch/April, M during 5% than less contributed a semipalatus Mylochromis ab anaphyrmus Mylochromis IHIA CICHLIDAE CICHLIDAE eebr (iue b. s pooto o h ttl nulwa rpeetd n ny 3 fte ace i srtm 2.1, stratum in catches the of 33% only in represented as w annual total the of proportion a catches. As 3b). incidental (Figure njassae sidered Synodontis December. a May/June gariepinus Clarias and arch/April M during 2% than less from ranged ab squamipinnis Oreochromis a lidole Oreochromis ab karongae Oreochromis Ctenopharynx pictus Ctenopharynx intermedius Ctenopharynx taeniatus Corematodus virginalis Copadichromis trimaculatus Copadichromis quadrimaculatus Copadichromis pleurostigma Copadichromis conophoros Copadichromis Copadichromis chrysonotus Copadichromis euchilus Cheilochromis The genus genus The Six Six oaiho is Copadichrom adc o is rom dich pa o C sp. 'blue orange' 'blue sp. 'gold' sp. pdcrmis opadichrom C a

a otiue moe hn % t te total the to 5% than ore m contributed

b b

a

ab b a ab ab

otiue 75 n 1.% o h n i 1%o h ace i srtm 31 Te otiuin of contribution The 3.1. stratum in catches the of 18% in and the to 11.6% and 7.5% contributed ab a

a

species (C. (C. species

a

b ab

ab a a

ab curd n ad 4 of 64% and % 8 6 in occurred chilimira net catches in strata 2.1 and 3.1 of southern Lake Malawi between March 2000 and February February and 2000 March between Malawi Lake southern of 3.1 and 2.1 strata in catches net hyoou, C. chrysonotus, and aculatus m oohrs C persima pleurostigm C. conophoros, aculatus quadrim tri- C. aculatus, quadrim C. a, pleurostigm C. conophoros, pdcrmis opadichrom C between periods. In stratum 2.1 the contribution of of contribution the 2.1 stratum In periods. between Rhamphochromis longiceps ab longiceps Rhamphochromis Rhamphochromis esox abesox Rhamphochromis Engraulicypris sardella ab sardella Engraulicypris Pseudotropheus livingstonii ab livingstonii Pseudotropheus ab elegans Pseudotropheus b taeniolatus Protomelas a similes Protomelas Placidochromis subocularis ab subocularis Placidochromis SILUROIDEI MORMYRIDAE CYPRINIDAE oodia w Stigmatochromis ab benthicola Sciaenochromis ceohoi lia h a Scaenochromis ab macrophthalmus Rhamphochromis Rhamphochromis feroxab Rhamphochromis Otopharynx speciosus ab speciosus Otopharynx a auromarginatus Otopharynx ab argyrosoma Otopharynx Trematocranus brevirostris Trematocranus praeorbitalisa Taeniolethrinops Tramitichromis lituris b lituris Tramitichromis b holotaenia Taeniochromis . chrysonotus C. . kiwingae, D. and and catch in stratum 2.1 and 3.1, respectively. respectively. 3.1, and 2.1 stratum in catch miicrmis idiochrom im D . virginalis) C. otiue 1.% ad 05 o h total the to 10.5% and 12.5% contributed

ab oaiho is Copadichrom hc cnrbtd .% ad .% to 6.9% and 6.0% contributed which and and a . virginalis C. r ietfe i te ac. Of catch. the in identified ere w and and wa rpeetd y single a by represented as w catch in both areas. areas. both in catch . rmaculatus trim C. dmiae te catch the inated dom wee con­ ere w D. C. C. 5 Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 tum 2.1, w hile in stratum 3.1 its contribution to the catch var­ catch stra­ the to in periods contribution all its 3.1 during stratum catch in the hile w to % 2.1, 6 tum than Consequently, less 2.1. tributed stratum from catches the 3). (Figure catch the to Cichlids i n ae ing kiw Table 2: Percent contributions of cichlid and non cichlid genera to the the to genera cichlid non and cichlid of contributions Percent 2: Table 6 al catch of each net. Missing values denote the absence of the genus from the sample; 0.0 denotes that the genus contributed <0.05% to the to <0.05% contributed genus the that denotes 0.0 sample; the from genus the of absence catch the denote values Missing net. each of catch al ent in 78% of the catches in stratum 3.1, but in only 34% of of 34% only in but 3.1, stratum the in to 3% catches 2). only the (Table of 2.1 78% contributed in stratum but ent in ) (>13% catch 3.1 annual stratum in catch all species, during catch the to <3% contributed it 3.1 stratum In 3). eu 1P 3P 5P 1P 3P 5P A P6 P5 P4 P3 P2 P1 A P6 P5 P4 P3 P2 P1 Genus (P4); 2000 September/October (P3); 2000 June/July (P2); 2000 May/June (P1); 2000 March/April periods: bi-monthly six during Malawi e fo 42 rm Se e / t t Jnu ry/ ua Jan to r e b cto r/O e b tem ep S from <4.2% from ied >17% contributed it hen w (Figure ber ecem January/February, ber/D ovem except N periods during >16% to arch/April M Non-Cichlids eid tau . Srtm 3.1 Stratum 2.1 Stratum Period annu­ the to genus each of contribution the of (A) estimate annual an and (P6), 2001 January/February and (P5) 2000 November/December ndniidjvnl ihis000.0 0.0 cichlids juvenile Unidentified Aulonocara Alticorpus Buccochromis Labeo Engraulicypris Bathyclarias Barbus Bagrus Pseudotropheus Protomelas Placidochromis Nyassachromis Nimbochromis Naevochromis Lethrinops Hemitaeniochromis Fossorochromis Diplotaxodon Dimidiochromis Mormyrus Synodontis Stigmatochromis Sciaenochromis Rhamphochromis Maravichromis Opsaridium Clarias Otopharynx Oreochromis Ctenopharynx Corematodus Copadichromis Cheilochromis Trematocranus Tramitichromis Taeniolethrinops Taeniochromis The genus genus The to the total catch ranged from < 1% during during 1% < from ranged catch total the to . sardella, E. ngraulicypris E which w as a m ajor contributor to the the to contributor ajor m a as w which 467. 811. 602. 5103010802140.7 1.4 0.2 0.8 0.1 0.3 45.1 29.7 26.0 18.2 38.1 74.9 74.6 01912. 432. 012. 584. 167. 485. 57.3 57.6 44.8 72.7 21.6 49.5 55.8 25.2 30.1 29.7 54.3 26.1 9.1 10.1 ...... 2.5 3.2 0.3 2.3 1.5 4.8 2.6 0.7 0.4 0.6 1.7 0.2 1.3 0.2 0.1 0.1 2.0 0.1 2.8 0.5 3.1 1.5 3.3 1.0 0.4 0.4 0.2 2.5 . . . . 0.5 1.9 2.7 0.3 0.7 0.0 0.1 0.4 0.1 . . . . 0.0 0.0 2.3 4.8 0.4 0.6 2.3 0.1 0.1 1.1 0.6 0.2 0.0 0.1 1.1 0.0 0.3 0.0 3.6 0.0 0.0 1.0 6.3 0.3 0.2 0.0 0.0 0.4 5.8 1.4 0.0 0.0 0.1 0.0 0.0 0.0 0.1 0.0 0.1 7.2 0.0 0.0 4.6 2.4 0.0 0.5 0.0 0.1 0.1 0.0 6.9 0.0 0.0 0.4 17.4 12.0 0.0 0.0 0.0 0.0 0.0 4.4 0.0 0.1 0.1 0.2 0.6 0.0 0.7 0.0 0.3 0.1 0.1 0.0 0.0 0.3 0.2 0.0 0.6 0.2 0.2 0.0 0.0 0.0 3.0 1.6 0.0 0.0 0.1 6.0 3.5 0.1 2.9 0.4 0.0 0.3 0.1 0.0 16.5 5.5 0.2 1.7 0.0 0.1 9.9 0.9 1.9 0.4 2.4 0.2 0.0 0.8 0.0 0.5 . . . . 621. . . . . 124. . 11.6 9.8 41.5 11.2 4.8 2.4 1.8 7.5 11.0 16.2 3.3 8.7 1.3 1.3 ...... 0.1 0.4 0.5 0.7 2.0 6.0 1.6 0.4 9.8 0.1 1.9 is monotypic, with a single single a with monotypic, is ...... 0.0 0.0 0.0 0.4 0.2 0.1 0.7 0.3 0.4 . 0.0 0.2 ...... 184. 8042051913.4 1.9 0.5 4.2 68.0 42.1 31.8 3.1 5.7 5.3 2.5 0.4 1.1 . sardella E...... 0.2 0.4 0.1 0.7 1.9 0.1 1.0 0.3 0.3 0.1 0.3 0.8 . sardella E. wa pres­ as w . . . 1.1 0.1 0.6 0.0 . . . 0.0 0.0 0.0 0.0 0.3 0.0 0.0 con­ . 0.0 0.0 chilimira total annual catch w as negligible (<1%). O f the three three the f O (<1%). negligible as w catch annual total annual the year-1. In stratum 3.1, the contribution of this genus to the the to genus this of contribution the 3.1, stratum In year-1. (Figure 3). 3). (Figure esti­ as w species this of catch annual total The 3). (Figure in more than 75% of all catches and contributing between between contributing and occurring catches .1, 2 all of stratum in 75% fishery than the of more in ponent com portant im responded to an annual catch of more than 8.5 tons net-1 net-1 yasalapia' 'N tons is 8.5 reochrom O than more of catch annual an to responded tons 4.2 and 2.1 July stratum to 3.1. in March year-1 stratum in net-1 from year-1 tons net-1 68% 0.5 at and mated 31% between to February, 18% and 75% to the catch com position during all periods periods all during position com catch the to 75% and 18% The genus genus The e ace ape i srt 21 n 31 n oten Lake southern in 3.1 and 2.1 strata in sampled catches net hlmira chilim ecrmi ' yasalapia' 'N is reochrom O ecrmi ' yasalapia' 'N is reochrom O cth n tau 21 Tbe2 hc cor­ which 2) (Table 2.1 stratum in catch . . 0.0 0.0 0.0 . . 0.0 0.0 0.1 species, tw o species species o tw species, 0.0 el Kzme Bohad Mandere and Booth Kazembe, Weyl, . . 0.0 0.1 0.2 . 0.0 0.0 contributed 45.1% to to 45.1% contributed w as the most most the as w . karongae O. Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 fia Junl fAutcSine20, 9 1-11 29: 2004, Science of Aquatic Journal African to the catch in stratum 3.1 during all periods (Figure 3). On On 3). (Figure periods all during 3.1 stratum in catch the to lidole bv br rpeet h nme o ace smld uig each during sampled catches of number the represent bars Numbers above 'other'. group February the into to lumped 2000 were species March other All from 2001. Malawi Lake southern in 3.1 (b)stratum and 2.1 stratum (a) in sampled fishery net chilimira inthe species Oreochromis Engraulicypris, Dimidiochromis, and and period by composition catch Percent 3: Figure 86% and 92% of all catches assessed in strata 2.1 and 3.1, 3.1, and than 2.1 strata more in in assessed represented catches as all w of genus 92% 77% and the and 86% basis, 21% between annual and an 2.1 stratum in not three catch as w the the to genus 54% of the within individuals position further. com ature m im assessed species the identifying species, in difficulty respectively. As a percentage of the annual annual the of percentage a As respectively. I I a hcrmis phochrom ham R . qa ipinnis squam O. w as only recorded in stratum 2.1. Due to the inherent inherent the to Due 2.1. stratum in recorded only as w O ther ther O ecrmis reochrom O Mar./ May/ Jul./ Sep./ Nov./ Jan./ Jan./ Nov./ Sep./ Jul./ May/ Mar./ p. u. u. c. e. Feb. Dec. Oct. Aug. Jun. Apr. I nruiyrs hmpoho is phochrom Rham Engraulicypris w ere recorded in both strata, w hile hile w strata, both in recorded ere w species contributed between 9% and and 9% between contributed species BIMONTHLY PERIOD BIMONTHLY Di dohr is\U m ro idioch im \D and and I Cpdcrmis \Copadichrom Rhamphochromis hlmira chilim Copadichromis catch, O. ,

ee rsn i apoiaeyeul rprin i h catch. the in proportions equal approximately in present were catch annual total the of 54% and 25% prised com genus this All four species w ere represented in stratum 2.1, with with 2.1, stratum in represented ere w species four All total four sub-samples, these ithin W com­ ple respectively. sub-sam a 3.1, on and 2.1 ta performed was level species to tion h ana cth n ocre i 2% ad 2 fal catch­ all nothrissa, of lim 42% and 28% in occurred and catch annual the in catches all of 5% and 21% in occurred and catch total the The length frequency distributions for for distributions frequency length The Two Two us acropthalm m tmtrt. n tau ., h lnt feuny distribution frequency length the 3.1, stratum In at-maturity. analysis Length-frequency a considered ere w further. and 3.1 discussed stratum in <1% and 2.1 stratum catches sampled and contributed 2.5% to the annual catch. catch. annual the to all of 2.5% 35% in contributed present and was it 3.1 sampled stratum In catches (<1%). 2.1 stratum of contributions ative is phochrom Rham is phochrom Rham genus the to belonging species 92.3% of annual annual of 92.3% and ) (98.8% is uccochrom B nototaenia taeniatus B. identified; ere w lepturus, B. species Four atritaeniatus, respectively. B. 3.1, and 2.1 strata catches all of 4% and 12% respectively. 3.1 in and 2.1 strata in occurred assessed which and catch meridionalis, B. s ria la c y th a B Diplotaxodon, respectively. agrus, B 17.8% and 66.4% 15.6%, were catches esox and and es sam pled from strata 2.1 and 3.1 respectively. Four Four respectively. 3.1 and 2.1 strata from species, pled sam es modal in stratum 2 .1, with the first mode before the length- length- the before mode first the with .1, ferox 2 R. stratum in strata. nothrissa, lim modal species, between D. target virginalis, considerably C. ajor m differed the 4, of Figure s in histogram illustrated not Length-frequency are they reason, this For fishery. the in by-catch inor m respectively. 3.1, and 2.1 strata in Opsaridium all of 27% and 14% prising im portant species within this genus, com prising 69.1% and and 69.1% prising com genus, this within species portant im in occurred and catch annual the of 2.3% and 3.6% prised an constitute fishery. the genera in these by-catch Therefore, portant 2). im (Table respectively of contribution relative the 3.1, stratum In respectively. 9 ad % fal ace i srt . ad ., respectively. 3.1, and 2.1 strata in catches all of 9% and 19% h rmann 7gnr otiue <% otecth in catch the to <4% contributed genera 27 aining rem The The genus genus The genus The genus The genera, other five of contributions annual bined com The Due to com plications with the accurate identification of of identification accurate the with plications com to Due Despite occurring in 17% of the catches, the genus genus the catches, the of 17% in occurring Despite Opsaridium , . cohhl us acrophthalm m R. hmpoho is phochrom Rham . ferox R. (45.8% ) and and ) (45.8% . retu, . iee D greenwoodii, D. bigeye, D. argenteus, D. ws mnrcmpnn fte ihr b ms in mass by fishery the of ponent com minor a was w ere identified. identified. ere w . rhoadesi B. r 1% n 9 n taa . ad 3.1 and 2.1 strata in 9% and 11% ere w and and catch. In stratum 3.1, only only 3.1, stratum In catch. which contributed 2% and 0.1% to the total total the to 0.1% and 2% contributed which Bagrus was a minor com ponent (<0.3% ) of the the of ) (<0.3% ponent com minor a was coho is uccochrom B iplotaxodon D species, species, iplotaxodon D cth n oh ra. n tau ., h rel­ the 2.1, stratum In areas. both in catch species, . longiceps R. . sx R ferox R. esox, R. was represented by a single species, species, single a by represented was catch were 3.2%, 7.1% and 89.5% 89.5% and 7.1% 3.2%, were catch , . lepturus B. (.%)wee identified. ere w ) (1.2% were identified in both strata. strata. both in identified were . microlepis O. coho s Oparidium psa O is, uccochrom B hmpoho is phochrom Rham . esox R. contributed 1.6% and 2.4% to to 2.4% and 1.6% contributed com prised 1.5% and 2.0% of of 2.0% and 1.5% prised com . i nothrissa lim D. landings. to the total total the to Rhamphochromis, (44.5% ), dom inating the the inating dom ), (44.5% , and and and and . ferox R. and and . udi aculatus, quadrim C. R. longiceps R. and and . macrocephalus O. Bathyclarias hmpoho is phochrom Rham . esox R. samples in stra­ in samples w as the most most the as w , . longiceps R. . rhoadesi. B. . lepturus B. identifica­ w ere bi- bi- ere w and and . atri­ B. to the the to and and com­ D. R. R. 7

Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 10 2 LLI 20 z O tribution is skewed, rising rapidly to 200m m TL and then then and TL m 200m to of rapidly tribution rising skewed, is tribution parison com eaningful m for 3.1 stratum in ples length-at- sam the catch after the occurring mode the with odal unim was fore be described as unim odal with the mode occurring occurring mode the with odal unim as described be fore and Turner 1977, Thompson Thompson 1977, Turner and 3.1 stratum and 2.1 strata in fishery net chilimira the from sampled 8 ne bten taa Tbe 3). (Table strata between ences ira chilim dis­ length-frequency The TL. m 400m to gradually declining 5. Figure in sented 2001. February and 2000 March between Malawi Lake southern in ferox Rhamphochromis b), for Length-frequency 4: Figure eoe maturity. before agd rm 1040mm Lad hi lnt-rqec dis­ of length-frequency n tio u their and distrib TL m 00m cy n e 100-4 u q fre from ranged length yasalapia' The 'N is reochrom strata. O een betw 4). (Figure aturity m (Tweddle literature the from derived (L50) was Length-at-maturity Copadichromis virginalis Copadichromis The length-frequencies of other m ajor species in the the in species ajor m other of length-frequencies The Insufficient Insufficient 20 20 10 15 10 10 15 10 5 5 1 1 2 2 5 0 5 20 15 10 5 25 20 15 10 5 (j) (j) (e) (g) i s . j e cth r ui dl ih o icril differ­ discernible no with odal unim ere w catch net 1 1 J « - ecrmi ' yasalapia' 'N is reochrom O TAU . TAU 3.1 STRATUM 2.1 STRATUM - i t P ci = 183 1 = n ecrmi ' yasalapia' 'N is reochrom O A 50 ji i ecrmi ' yasalapia' 'N is reochrom O (g, h) and and h) (g, 50 = 09 40 1 009 = n OTL EGH (cm) LENGTH TAL TO =84 4 854 = n = 189 = n aculatus quadrim C. (c, d), (c, i cthsfo srtm . i pre­ is 2.1 stratum from catches in . i nothrissa lim D. et al. et qdl . longiceps R. . virginalis C. 74 Copadichromis quadrimaculatus Copadichromis . ferox R. 1996b, Turner Turner 1996b, Rhamphochromis longiceps Rhamphochromis Diplotaxodon limnothrissa Diplotaxodon 20 20 10 15 10 15 5 5 - o h cth a h re­ the can catch the of

1 l50 l 218 =n r-nr^nr-^ n j n = 735 = n

L50 r peet in present ere w r-v-TV-nl i j

et al. et T1 in the catch catch the in 2000) i ° 5 U- tU n = 288 =n =343 n = 185 = n - h e f), (e, (J) (h) (d) (d) (b) (f) (i, j)(i, • .It t f e (a, hrfr, h frtassmeto h lgtatato cmpo­ com light-attraction the of ent assessm first the therefore, Discussion al o te ih-trcin ihr. h cret td is, study current The fishery. by the data light-attraction ting catch the targe on cally groups disaggregate or to fishing species pted attem assessing (1998) Smith nent of the the of nent Engraulicypris sardella Engraulicypris greenwoodii Diplotaxodon argenteus Diplotaxodon kiwingae Dimidiochromis Buccochromis Bathyclarias meridionalis Bagrus sition) with unimodal length-frequency distributions in the the in distributions total length-frequency (mm unimodal with deviation sition) standard ± capture at length Mean 3: Table for maturity at ranges the karongae represents (L50) range at-maturity the from sampled Rhamphochromis macrophthalmus Rhamphochromis esox Rhamphochromis capture at length Mean Species e ac i suhr Lk Malawi Lake southern in catch net compo­ catch the to >4% contributing genera (in species of length) (1983) for Length-frequency 5: Figure Opsaridium microcephalus Opsaridium microlepis Opsaridium trimaculatus Copadichromis pleurostigma Copadichromis conophoros Copadichromis chrysonotus Copadichromis Lake Malawi between March 2000 and February 2001. The length- length- The 2001. February and 2000 March between Malawi Lake ^ tr LLI a ZD LLI z a >- 5 15 10 10 13 16 19 22 25 28 31 34 37 40 40 37 34 31 28 25 22 19 16 13 10 , . lidole O. hlmira chilim sp 9 ± 165 ± 493 spp. . sardella E. spp. 220 ± 45 ± 220 spp. chilimira and and fishery. Estim ates of CPU E and effort for effort and E CPU of ates Estim fishery. eaaey bt i nt ou specifi­ focus not did but separately, OA LNT (cm) LENGTH TOTAL . squamipinnis O. net fishery in stratum 2.1 in southern southern in 2.1 stratum in fishery net rohoi ‘Nyasalapia’ Oreochromis el Kzme Bohad Mandere and Booth Kazembe, Weyl, I derived from Trewavas Trewavas from derived m L SD) ± TL (mm _ 0 6 ± 7 ± 260 84 ± 269 64 ± 212 74 ± 233 33 ± 206 40 ± 204 141 ± 432 8 ± 34 ± 184 17 ± 136 22 ± 143 29 ± 142 n Q pdcrmis opadichrom C 2 16 ± 92 11 ± 85 = 3 282 3 = nn -r Innnm species species chilimira O.

Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 the fam ily C ichlidae, all species in the genera genera the in species all ichlidae, C ily fam the A llison 1997) such as as such 1997) llison A thus the reduced w ave-generation capacity during windy windy during capacity ave-generation w Due 2). reduced (Figure the stratum thus this in can­ period be this to over trips fishing observed as w cause even or curtail may ugust) A to than that recorded in stratum 3.1 but nets in stratum 2.1 2.1 stratum in nets but 3.1 stratum in recorded that than 1-11 29: 2004, Science of Aquatic Journal African 2002). Similarly, the predatory characid characid predatory the Similarly, 2002). Tanganyika, suggested that the predators w ere drawn to the the to drawn ere w predators the that suggested Tanganyika, for fishery ganyikae year. ferences in the two strata m ight explain the different CPUE CPUE different the explain ight m strata two the in ferences from stratum 2.1. CPU E in stratum 2.1 w as generally lower lower generally as w 2.1 stratum in E CPU 2.1. stratum from fished more frequently; this led to sim ilar annual catches catches annual ilar sim to led this frequently; more fished sidered truly pelagic (Thom pson and Allison 1997). W ithin ithin W 1997). is Allison and phochrom ham R pson (Thom pelagic truly sidered as for the catch of typically benthic predators (Tweddle (Tweddle predators benthic and typically pson era of (Thom catch piscivores the for of pelagic as presence the for abundant account less also ould w prey other, of concentration light-attraction the in by-catch considerable a constitutes (C ochrane 1976, C oulter 1976, Van Zw ieten ieten Zw Van sii 1976, ­ oulter C com ajor 1976, m a as ochrane (C predators of presence The 3). and 2 (Tables is idiochrom im D the Hence, (Tweddle 1997). stocks llison A and fluctuating pson Thom idely w 1990, and density-depend­ Lewis rate, and survival ortality m larval natural high ent a output, of ductive contribution low the (1998), Smith by sardella ented 25% docum and also 2.1% 2). stratum in (Table 11% only as w quantities fishery great the in in catch occurring es etim som catch, ira chilim effort fishing in reduction distinct a Consequently, celled. n effort. and (Sm ith 1998) but differed considerably from those derived derived those ates from estim previous considerably with differed but favourably 1998) pared ith com (Sm 3.1 stratum lamps from a w ider radius than w ere their clupeid prey. The The prey. clupeid their ere w than radius ider w a from lamps clupeids the targeting fishery light-attraction ponent o f light-attraction fisheries is w ell docum ented ented docum id ell w centropom is predatory the fisheries Tanganyika Lake light-attraction f o genus ponent the f o s lid cich previous gic the la in pe ent recruitm poor of consequence a be may of contribution low of contribution low the hile W annual 2). total is (Table the 3.1 opadichrom to C stratum contribution in bined com their However, is opadichrom C sta­ 2). relatively (Figure as w 2.1 year and the stratum lake of the throughout fishery of ble the in effort shoreline ost periods, southernm the to ity proxim its (May inter w in aves w wind-generated south-easterly large, en md i te wo taa Fgr 2. niometl dif­ ental Environm 2). (Figure strata o tw the in made being 1975, Lovullo Lovullo 1975, makes up a considerable proportion of the catch of the the of catch the of proportion considerable a up makes As w as the case with previous assessm ents of the the of ents assessm previous with case the as w As h mr ta 50 pce i te ae fw ae con­ are few lake, the in species 500 than more the f O C o u lte r (1976), w o rking on on rking o w (1976), r lte u o C . sardella E. Despite relatively low low relatively Despite where offshore operate generally 3.1 stratum in Fishers coho is uccochrom B wa surprising. as w net fishery (Lewis and Tweddle 1990, Smith 1998), 1998), Smith 1990, Tweddle and (Lewis fishery net and and . iodon m L. et al. et s fs-rwig pce wt a ag repro­ large a with species ing fast-grow a is to night catches of this fishery w as a feature feature a as w fishery this of catches night to and made up a considerable portion of the catch catch the of portion considerable a up made i ohis miodon m nothrissa Lim and and and and 1992, Turner 1996) belonging to the gen­ the to belonging 1996) Turner 1992, . sardella E. . sardella E. n ae aia Ccrn 1976). (Cochrane Kariba Lake in athyclarias B iplotaxodon D Bagrus. . sardella E. to the total catch in both areas areas both in catch total the to w ere w ell-represented in the the in ell-represented w ere w and and r plgc To pson (Thom pelagic are mphoc omis m ro ch o h p am h R . t rsii e p p sta L. (Van Zwieten Zwieten (Van catches, predatory predatory catches, paiim, Opsaridium doyu vittatus ydrocynus H Stolothrissa tan- Stolothrissa et al. et ae stapper- Lates in Lake Lake in 02. In 2002). as well well as and and t al. et E.

oa etn o hs avs i unknown. is is harvest lake this of the of extent total stock pelagic the that ption assum The tons. in catch the to 35% and 3.1% stratum in catch annual the dsra ad o i i dae agr f oaie over­ localised of danger ediate m im in not ent and anagem m idespread w thus and catch, the to fishery. 80% than ulti-species more m the in tribute species target least-resilient the concentration. fishing calised the lo to a vulnerable f o more is result genus a this as w Alternatively, 2.1 the tum that showed ho w (2001), Kanyerere by ed confirm specific. area ther is catch the in genus this of presence the that 1996 in Fisheries of ent epartm D Malawi the by taken year-1 and c. 18.6 tons net-1 year-1 in strata 2.1 and 3.1, 3.1, and 2.1 strata in year-1 net-1 tons 18.6 c. and year-1 Turner 1977, Trew avas 1983, Thom pson pson Thom 1983, avas Trew 1977, Turner under­ ent assessm rapid a 1998), (Smith A SW the in fishery tau 2.1. 2 stratum pson (Thom exploitation (Turner (Turner exploitation is phochrom ham R on ent anagem m base to is option possible one opti­ its cases at such species each anage m to possible im is it species, differs species target each as ent anagem data m its Unfortunately, plicates com grounds. fishing er shallow the in gear of contribution low indicates the 3.1 However, stratum in 3). catches to (Figure Boadzulu genus study the of of this south by contribution fishery supported the in are catch the to significantly juvenile that showed eyl (W 3.1 stratum in 142 and genera, cyprinid single a addition, In 1997). species, llison A and cham bo stock of the SEA w as concentrated south of of south concentrated as w SEA the of stock bo cham longer valid. However, due to the lack of lake-wide data, the no the data, therefore lake-wide is of lack 1997) the to due Allison However, and valid. pson 000 3 longer (Thom exceed could unexploited strata o tw these in catch species pelagic 94 of total a ith W respectively. zone pelagic the in quantities considerable in recorded m easures should focus on these genera. The pelagic pelagic The genera. these on focus should easures m In another. for suitable appro­ be of not levels ber may num harvest a species because one 1984) harvests for priate urawski (M fishery level a mum when that, and recognised Tweddle 1960, (Iles aturity m and growth shape, body in hypotheses. these testing prevented itations lim substantial the that possible therefore is It the Island. t a th Boadzulu d sise othe hyp ) 52 (19 Lowe the in by-catch occasional an as recorded genera been cichlid the to is m belonging ro ich d a species p o C i-pelagic sem prised genera, pson the Thom uroid during only 1960, returns (Iles pelag­ the then into and season TL areas 130mm breeding rocky about inshore at from zone ic igrates m it because 1996b, Turner Turner 1996b, yasalapia' 'N ent assessm rapid the of findings The 1996). (Banda Island yasalapia' 'N cnieal prin fte ac i srtm 21 o ­ com 2.1 stratum in catch the of portion considerable A The annual pelagic species catch is c. 6.8 tons net-1 net-1 tons 6.8 c. is catch species pelagic annual The hs td hs hw ta ls ta sx eea con­ genera six than less that shown has study This fishery attraction light the of nature ulti-species m The . drmaul us, tu la acu rim ad u q C. et al. et stocks w ere localised. This hypothesis w as fur­ as w hypothesis This localised. ere w stocks hile W 2). (Table ecrmi ' yasalapia 'N is reochrom O t al. et , Bathyclarias 1996b). Pelagic species contribute 79% to to 79% contribute species Pelagic 1996b). ngraulicypris E and and mi oc omis m ro ch io id im D et al. et 2000, Smith 2000). It has long been been long has It 2000). Smith 2000, ecrmi ' yasalapia' 'N is reochrom O iplotaxodon D 2000) and and 2000) and and ecrmi ' yasalapia' 'N is reochrom O and and t al. et hlmira chilim is con sid ered pelagic, pelagic, ered sid con is Synodontis, 2002), the total annual annual total the 2002), and and psaridium O . sardella E. stocks are considered considered are stocks nets in stratum 2.1 2.1 stratum in nets t tecth n stra­ in catch the 'to t al. et oaiho is Copadichrom t al. et 1996a). Two Two 1996a). have been been have ecrmis reochrom O nmbr are bers num ec o is rom reoch O , and two sil- sil- two and , contributed contributed 1996a, 1996a, hlmira chilim has has 9

Downloaded by [University Of Rhode Island] at 12:46 10 July 2015 h apiain fsok ses n models. ent Acknowledgements assessm stock of application the this for interventions ent anagem m that indicates area on tion caution. with ed view be ust m area this area-specific. be to need genus this the that indicates 1983) (Trewavas aturity m at length the to here. priority ent anagem m a not therefore Although are genera three nothrissa supported by the Gesellschaft fur Technische Zusammenarbeit Zusammenarbeit Technische fur Gesellschaft the by supported a targets fishery the Since area-specific. be to need fishery aculatus m prior distribution length-frequency skewed the of mode The lidole O. gae, fishery. . ogcp, . ignls C qarmaculatus quadrim the C. of virginalis, proportion C. considerable a longiceps, R. mature, ere w 3.1 (GTZ GmbH, Eschborn) supported National Aquatic Resource Resource of Department Aquatic Malawi National the of (NARMAP) supported Programme Management Eschborn) GmbH, (GTZ logistically and financially was study this for fieldwork The lowship. for available are data fisheries and closure biological area or additional limitation as effort blage, assem species diverse nurs­ a in operate may fishery for this nursery area that of (Turner ery indicates use species 2.1 the cichlid stratum about i-pelagic localised sem to known and al. is pelagic by susceptible little not areas and idespread overexploitation, w considered are for interventions ent anagem m negligible, as w 3.1 and ass) stratum biom overall grown to have they significantly before fish contribute to young sufficiently capturing (by overfishing at aturity m attaining to prior offshore igrate m and areas this in ent anagem m of focus the be therefore should genera the on genus available the is of ation Species inform stock. its of published no status 1996), (Turner than rather factors ental environm by driven be to considered cern. The three main species w ithin this genus, genus, this ithin w species main three The cern. FAO 1952, (Lowe ented docum locality-spe­ been and has 1996) Turner 1983, overfishing cific Trewavas 1952, (Lowe m ajority of the other target species in the fishery of stratum of fishery the in species target other the of ajority m Lake Malawi, whose co-operation facilitated this study. this of facilitated fishermen the co-operation to whose thanks Malawi, Lake sincere our express also We Fisheries. fel­ Post-Doctoral University Rhodes a of award the for University time such until options, ent anagem m viable only the be may in catches to genus spawner this of of reduction contribution the excessive Since (by biomass). overfishing growth ent both recruitm ards tow contribute may fishery 1990). light-attraction Lewis 1983, nursery (Trewavas TL as m 220m zone littoral exceeding lengths inshore the use which planktivores yasalapia' 'N is reochrom O These 1997). llison A and pson (Thom ortality m fishing by 10 Nyasalapia' 'N Tweddle 1993, 00. ic te i dl egh rqec srcue in structure frequency length odal bim the Since 2000). A lthough the the lthough A The dependence of catch-com position and size-selec- size-selec- and position catch-com of dependence The The predom inance of ju veniles in the the in veniles ju of inance predom The Furtherm ore, it w as interesting to note that, w hile the the hile w that, note to interesting as w it ore, Furtherm avse i srtm . weejvnls Fgr 3). (Figure juveniles ere w 2.1 stratum in harvested and and ingae kiw D. catch in stratum 2.1 (Figure 5) is cause for con­ for cause is 5) (Figure 2.1 stratum in catch . eo, . ogcp, . ignls C quadri­ C. virginalis, C. longiceps, R. ferox, R. and and . i nothrissa, lim D. t al. et a hcrmis phochrom ham R — OLF Weyl would like to thank Rhodes Rhodes thank to like would Weyl OLF — . qa ipinnis, squam O. 1994, W eyl 2000, 2001). These two two These 2001). 2000, eyl W 1994, is distributed throughout the lake lake the throughout distributed is are more limited in distribution distribution in limited more are xaso o h fsey in fishery the of expansion and and are schooling phyto- phyto- schooling are iplotaxodon D pdcrmis opadichrom C ecrmis reochrom O and and . karon- O. . er x ro fe R. stocks stocks . i - lim D. and and et ,

A AKO PN 20) rswtr ihr rsac ognstos in organisations research fishery JACKSON Freshwater (2000) PBN C C C References B B B B B E L K I H Lake of arm south-east the in management Fisheries (1993) FAO L L s e l o l l u v o is w e is w e e r e r e y n a a d n a n o l a son o is l l a d n a d n a l k c u rani n a ir l u n o r f r e t l u o e n a r h c o r e t l u o d r a w o the development and management of fisheries on Lake Malawi. Malawi. Lake on fisheries of management and development the ta — — ta Aquatic Resource Management Programme, Short Short Programme, 811-817. 40: Management Resource Aquatic Administration, London, pp 5-22. pp London, Administration, Technische Zusammenarbeit/Government of Malawi — National National — Malawi of Zusammenarbeit/Government Technische n Mnmnso hdsa Krb Suis7 98-108. 7: Studies Kariba Rhodesia, of Monuments and 235-259. and species commercially important fish species in the Southeast and and Southeast the in species fish important commercially 15-20. 55: Africa South Transactions of Society recollection. Royal the of personal a Africa: eastern and central Haplochromis statistical of measures 54-77. 1: other Science and Statistical accuracy. intervals, confidence errors, n Mlme 15-95 I: ice T ad olnwrh CE Hollingworth and TJ Pitcher In: 1859-1985. Malombe, and Agricultural and Food Ntions United 21, No. Paper. Technical Vol 1. Overseas Development Administration, London, pp 57-66. pp London, Administration, Development Overseas 1. Vol sardella) a brood of of brood a Management Challenge. Fountain Press, Kampala, pp 49-69. pp Kampala, Press, Fountain Challenge. Management Communication No. 3, 6pp. 3, No. Communication ing sardine fishing operations in Lake Kariba. National Museums Museums National Kariba. Lake in operations Malawi, fishing sardine ing of Government report. Resource waters: Malawian M method for catching light-attracted fish in Lake Tanganyika. Tanganyika. Lake in fish light-attracted catching for method Southwest arms of Lake Malawi: A geostatistical analysis. Malawi Malawi analysis. geostatistical A Malawi: Lake of arms Southwest Occasional Papers, vol 1. Overseas Development Development Overseas 1. Malawi. vol in Research Papers, Fisheries on Reports Occasional Collected (eds) (Oreochromis 113pp. Rome, Organization, chambo on fisheries the to particular with reference Malombe, Lake and River Shire Upper the Malawi, (1985-1986). In: Pitcher TJ and Hollingworth CE (eds) Collected Collected (eds) CE Hollingworth and TJ Pitcher In: (1985-1986). n Ghb ad ac M (d) fias nad ihre: The Fisheries: Inland Africa's (eds) MT Sarch and K Geheb In: Unpublished internal report, Malawi Department of Fisheries. of Department Malawi report, internal Unpublished Fisheries resource user-groups in Malawi. Gesellschaft fur fur Gesellschaft Malawi. in user-groups resource Fisheries ultn aba : 175-186. 5: Zambia Bulletin, ihre Dprmn, ihre eerh nt 54pp. Unit, Research Fisheries Department, Fisheries Lake Tanganyika, and the status of the pelagic fishery for for fishery pelagic the of status the and Tanganyika, Lake 215-224. 5: Zambia Bulletin, Research Fisheries ihre Blei N. 3 30pp. 43, No. Bulletin Fisheries 257-280. 13: History Natural Annual Organisation, Research Fisheries 11: 71-73. Report Joint Nyasa. Lake Reports on Fisheries Research in Malawi. Occasional Papers, Papers, Occasional Malawi. in Research Fisheries on Reports

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