7KHFRPPHUFLDOÀVKHU\RIWKHPLGGOH1\RQJ5LYHU&DPHURRQ SURGXFWLYLW\DQGHQYLURQPHQWDOWKUHDWV

Randall E. Brummett1, David Nguenga2, François Tiotsop3 & Jean-Claude Abina4

1WorldFish Centre, BP 2008 (Messa), Yaoundé, . 2Institut de Recherche Agricole pour le Développement (IRAD), Unité de Recherches Piscicoles et Halieutiques, BP 255 Foumban, Cameroun. 3Ministere de l’Elévage, des Pêches et des Industries Animales, BP 11143, Yaoundé, Cameroon. 4Faculté d’Agronomie et des Sciences Agricoles, University of Dschang, BP 38, Dschang, Cameroon.

Submitted 9 October 2008; accepted 6 July 2009.

ABSTRACT.)LVKLQJPHWKRGVFDWFKHVÀVKVSHFLHVGLYHUVLW\ZDWHUTXDOLW\DQGGLHWVZHUHH[DPLQHGLQWKH PLGGOH1\RQJ5LYHUEDVLQRIVRXWKFHQWUDO&DPHURRQRYHUÀYH\HDUV2XWRILQGLJHQRXVVSHFLHVIURP WKHXSSHUDQGPLGGOH1\RQJLQPXVHXPFROOHFWLRQVLQGLJHQRXVVSHFLHVDGGHGLQWKLVVWXG\ WRWDO   DQGWZRIHUDODOLHQVSHFLHVRQO\DUHUHJXODUO\FDSWXUHGE\FRPPHUFLDOÀVKHUVDQGRQO\RIWKHVHDUH VXIÀFLHQWO\DEXQGDQWDQGODUJHHQRXJKWREHRILPSRUWDQFHDVIRRGÀVK7ZRRIWKHPRVWLPSRUWDQWDUHWKH alien Oreochromis niloticus and Heterotis niloticus,QWKHVHDVRQÀVKHUVÀVKHGDQDYHUDJHRIGD\V SHU\HDUZLWKD&38( NJÀVKHUGD\([WUDSRODWHGDQHVWLPDWHGÀVKHUVFDWFKWRIÀVKSHU DQQXP NJKDRIZDWHUVKHG 'HVSLWHLQWHQVLYHVDPSOLQJVSHFLHVSUHYLRXVO\UHSRUWHGIRUWKH1\RQJ ZHUHQRWUHFDSWXUHGGXULQJWKLVVWXG\0RVWFRPPHUFLDOO\LPSRUWDQWVSHFLHVDUHGHWULWXVDQGRUDTXDWLF DUWKURSRGVIHHGHUVZLWKDKLJKOHYHORIGLHWDU\RYHUODSEXWREVHUYHGRYHUODSEHWZHHQWKHPRVWFRPPRQ FRPPHUFLDOVSHFLHVDQGWKHLQWURGXFHGDOLHQVLVORZ$OWKRXJKTXDQWLWDWLYHGDWDDUHODFNLQJRQWKHVWDWHRI WKHHFRV\VWHPDWWKHWLPHRIHDUOLHUÀVKFROOHFWLRQVWKHUHLVFLUFXPVWDQWLDOHYLGHQFHWKDWLQGLJHQRXVVSHFLHV PD\KDYHVXIIHUHGIURPFRPSHWLWLRQZLWKLQWURGXFHGDOLHQVDQGRUFKDQJHVLQWKHHFRV\VWHPUHVXOWLQJIURP SRRUODQGXVHPDQDJHPHQWDQGWKHXVHRISHVWLFLGHVLQÀVKLQJ

KEYWORDS/RZHU*XLQHD 5DLQIRUHVWÀVKELRGLYHUVLW\GLHWDU\RYHUODS

,1752'8&7,21 mean pH of 6.2, hardness of <10 mg/l (as CaCO3) and HOHFWULFDOFRQGXFWLYLW\EHWZHHQDQGPS/cm. Water 7KH 1\RQJ 5LYHU LV LQ WKH /RZHU *XLQHD (TXDWRULDO WHPSHUDWXUHLVDOZD\VEHWZHHQDQGƒ&7KHZDWHU )RUHVWRQHRIWKHZRUOG·VROGHVWDQGPRVWELRGLYHUVH is naturally clear and tea-coloured as a result of the HFRV\VWHPVZLWKDERXWVSHFLHVRIÀVK %UXPPHWW ORZ GLVVROYHG QXWULHQW FRQFHQWUDWLRQ ORZ OLJKW GXH & Teugels 2004; Stiassney et al RIZKLFKDUH WRQDUURZQHVVRIYDOOH\VDQGFDQRS\FRYHU DQGKLJK HQGHPLF +XJXHQ\ /pYrTXH 7KH1\RQJÁRZV tannin concentrations leaching from the large amount NPZHVWDQGVRXWKIURPLWVSRLQWRIRULJLQWRWKH RIDOORFKWKRQRXVYHJHWDWLYHPDWWHUWKDWIDOOVRUÁXVKHV east of Abong-Mbang in the tropical rainforest of east- LQWRWKHZDWHUIURPWKHVXUURXQGLQJIRUHVW :HOFRPPH central Cameroon, discharging an annual average of & de Merona 1988). 443 m3VHFLQWRWKH*XOIRI*XLQHDDWWKHVPDOOLVODQG $VIRUPRVWRIWKH/RZHU*XLQHDIRUHVWWKHUHH[LVWV ÀVKLQJYLOODJHRI%HKRQGR )LJ 7KHKHDGZDWHUVOLH for the little biological or ecological very close to those of the Congo River Basin, and hence information, nor any sort of practical management WKHWZRV\VWHPVVKDUHDFHUWDLQDPRXQWRIELRGLYHUVLW\ SODQ WKDW PLJKW WUDFN FKDQJHV LQ WKH HFRV\VWHP 7KH 7HXJHOV *XpJDQ 7KHPDMRUDIÁXHQWVWUHDPV 1\RQJ%DVLQKDVDOUHDG\ORVWDQHVWLPDWHGRILWV to the Nyong are the rivers M’foumou (entering from primary forest to logging and conversion to agriculture the North) and So’o (entering from the South), both DQGFRQWLQXHVWRORVHIRUHVWHGZDWHUVKHGDWDQDYHUDJH contributing to the river in its middle reaches. The UDWHRISHU\HDU 5HYHQJDHWDO /RJJLQJLQ EDVLQFRYHUVDSSUR[LPDWHO\NP2EHWZHHQƒ· &HQWUDO$IULFDLVXQGHUWDNHQLQDODUJHO\LUUHVSRQVLEOH DQGƒ·1ODWLWXGHDQGƒ·DQGƒ·(ORQJLWXGH manner that alters stream courses and increases runoff (Hugueny 1989). The climate is transitional equatorial DQG VLOWDWLRQ ,Q DGGLWLRQ URDGV VDZPLOOV DQG RWKHU ZLWKRQHVKRUW -XO\$XJXVW DQGRQHORQJ 'HFHPEHU LQIUDVWUXFWXUH DVVRFLDWHG ZLWK ORJJLQJ DWWUDFWV SHRSOH 0DUFK GU\VHDVRQDOWHUQDWLQJZLWKUDLQV )LJ  LQWRWKHIRUHVWUHVXOWLQJLQZKROHVDOHWUDQVIRUPDWLRQRI 7KH 1\RQJ LV D W\SLFDO ´EODFNZDWHUµ ULYHU ZLWK D WKHHFRV\VWHP %XUQV*DUPDQ 0RULQJ 

5 February 2010 4 BRUMMETT ET AL.

Fig. 1. Map of the Nyong River basin in Cameroon.

Fig. 2. 6HDVRQDOGLVFKDUJHRIWKHPLGGOH1\RQJ5LYHUDW0EDOPD\RLQGLFDWLQJWKHUHSRUWHGWLPLQJRISHDN¿VKLQJ (discharge data from SAGE 2003).

Improper use of agricultural pesticides has become identify potential threats to this and other tropical ZLGHVSUHDG DV D UHVXOW RI H[SDQGLQJ VPDOOVFDOH RLO UDLQIRUHVWULYHUVDÀYH\HDUVWXG\RIÀVKLQJJHDUVDQG SDOPFXOWLYDWLRQDQGLVHYHQXVHGDVDÀVKLQJPHWKRG WHFKQLTXHV ÀVK GLYHUVLW\ LQ FRPPHUFLDO FDWFKHV DQG Insecticides can be highly destructive of the entire food the diets of both indigenous and introduced species ZHEDQGKXPDQGHDWKVKDYHEHHQUHSRUWHGDVDUHVXOW ZDVFDUULHGRXWRQWKHPLGGOH1\RQJ5LYHULQVRXWKHUQ RIHDWLQJSRLVRQHGÀVK GX)HX  Cameroon. In addition, a number of alien species have been introduced, accidentally (by escape from aquaculture IDFLOLWLHV  RU RQ SXUSRVH WR HQKDQFH FDSWXUH ÀVKHULHV 0$7(5,$/6$1'0(7+2'6 into the Nyong. These robust and aggressive species (Oreochromis niloticus, Clarias gariepinus, Cyprinus carpio The section of the river here designated as the middle and Heterotis niloticus) are highly invasive and could Nyong (Fig. 3b) is that part that passes through represent a serious threat to indigenous biodiversity. UDLQIRUHVW EHWZHHQ WKH DOWLWXGHV RI  DQG  P 7R EHWWHU XQGHUVWDQG WKH ÀVKHU\ DQG DWWHPSW WR DERYH 06/ IURP D SRLQW DERXW  NP GRZQVWUHDP

Smithiana Bulletin 11: 3 - 16 &RPPHUFLDOÀVKHU\RIPLGGOH1\RQJ5LYHU&DPHURXQ 5

IURP 0DNDN ƒ· 1 ƒ· (  ZKHUH WKH 0SRXPp ZKRHPSOR\DUDQJHRIFDSWXUHPHWKRGV IDOOVVHSDUDWHWKHPLGGOHIURPWKHORZHUUHDFKHV )LJ $OOVDPSOHVZHUHPHDVXUHG 7/ WRWKHQHDUHVWPP F XSWR$NRQROLQJD ƒ·1ƒ·( DERYHZKLFK À[HG LQ  HWKDQRO DQG LGHQWLÀHG LQ WKH ODERUDWRU\ WKH XSSHU ULYHU RFFXSLHV D ODUJH VHDVRQDO ÁRRGSODLQ using Daget (1984), Vivien (1991), Mbega & Teugels (Fig. 3a). (2003), Paugy et al  *HHULQFN[et al. (2004), Ng 0RQWKO\ ÀVK VDPSOLQJ ZDV FRQGXFWHG EHWZHHQ (2004) and Stiassny et al  )LVKHVWKDWFRXOGQRWEH February 2001 and February 2006 at eight sites in the LGHQWLÀHGIURPWKLVOLWHUDWXUHZHUHVHQWWRWKH%HOJLDQ PLGGOH1\RQJZDWHUVKHG$NRQROLQJD ƒ·1ƒ· Royal Museum for Central Africa (MRAC) and/or the (  $QJD·D ƒ· 1 ƒ· (  0EDOPD\R ƒ· 1 American Museum of Natural History (AMNH) for ƒ· (  3RQW 6R·R ƒ· 1 ƒ· (  1·NRO (EDH LGHQWLÀFDWLRQ 6SHFLHV UHJXODUO\ DSSHDULQJ LQ FDWFKHV ƒ· 1 ƒ·(  1·WDQJ ƒ· 1 ƒ· (  $YqEH DQGPDUNHWHGZHUHGHHPHG´FRPPHUFLDOµZKLOHWKRVH ƒ  1 ƒ  (  DQG 0LQODED ƒ  1 ƒ  (  occurring only infrequently and/or predominantly 6DPSOHVFRQVLVWLQJRIDWOHDVWÀYHLQGLYLGXDOVHDFKRI XVHGIRUKRPHFRQVXPSWLRQZHUHFRQVLGHUHGE\FDWFK all species available on each sampling date and at each To quantify the catch, a 13-month study (July 2004 – VDPSOLQJVLWHZHUHFROOHFWHGIURPFRPPHUFLDOÀVKHUV -XO\ ZDVFRQGXFWHGDPRQJÀVKHUVLQWKHYLOODJHV RI3RQW6R·R1·NRO(EDH1·WDQJ $YqEH DQG 0LQODED ZKLFK DUH A UHSUHVHQWDWLYHRIWKHPDMRULW\RI VPDOOÀVKLQJFRPPXQLWLHVLQWKH middle Nyong basin. Fishers in WKHVHYLOODJHVH[SORLWDQXPEHU of rivers in the area, most importantly the Nyong, So’o, Fala, Bissi, Ossoe Koss, Soumou, Yenne, Nsono, N’tang Mebe 2VVRH %HYD·D $NRXPEHJXH Ossoe Bisseguê and Mimiteme. Of the 99 people reported by the ORFDO SRSXODWLRQ WR EH ÀVKLQJ IXOOWLPHLQWKHDUHD 7DEOH  agreed to participate in the creel VXUYH\DQGÀYH RQHIURPHDFK village) volunteered as data FROOHFWRUV DQG ZHUH HTXLSSHG ZLWK D VSULQJ EDODQFH DQG trained in completion of a basic survey form that captured data RQZHLJKWDQGYDOXHRIWKHFDWFK by species. B During each sampling YLVLW YLVXDO REVHUYDWLRQV ZHUH PDGH RI ÀVKLQJ DFWLYLWLHV gears employed and the general condition of the river. 6WUXFWXUHG LQWHUYLHZV ZHUH used to systematically collect LQIRUPDWLRQIURPÀVKHUVUHODWHG to catch and environmental trends. In addition, measure- ments of temperature and GLVVROYHG R[\JHQ ZHUH PDGH ZLWK D 6HQWU\ ,,, 2[\JHQ Temperature Monitor, and ZDWHUVDPSOHVZHUHFROOHFWHGIRU later measurement of electrical FRQGXFWLYLW\ ZLWK D EHQFKWRS TPS 900C EC meter. To quantify the natural diet of commercially important species,

5 February 2010 6 BRUMMETT ET AL.

C

Fig. 3. The upper Nyong River at in June (A), middle at Mbalmayo in March (B), and lower at Song Abwé in October (C). Photos: R E Brummett.

Table1.1XPEHURIKRXVHKROGV¿VKHUV¿VKWUDGHUVDQGFDQRHEXLOGHUVLQ¿YHW\SLFDO¿VKLQJFRPPXQLWLHV HQJDJHGLQWKHFRPPHUFLDO¿VKHU\RIWKHPLGGOH1\RQJ5LYHUEDVLQ

VWRPDFKV RI  LQGLYLGXDOV WZR ÀVK RI HDFK VSHFLHV SHUPRQWKEHWZHHQ)HEUXDU\DQG)HEUXDU\  5(68/76$1'',6&866,21 ZHUHGLVVHFWHGDQGÀ[HGLQIRUPDOLQ)RUVSHFLHV ZLWKQRWUXHVWRPDFK HJLabeo lukulae) the upper 5 cm The middle Nyong river is special in Cameroon for RIWKHGLJHVWLYHWUDFWZDVWDNHQ6WRPDFKFRQWHQWVZHUH WZR LPSRUWDQW UHDVRQV   8QOLNH WKH ELJ FRDVWDO DQG analysed according to the frequency of occurrence ODUJHUULYHUÀVKHULHVRQWKH6DQDJDDQG%HQXH5LYHUV PHWKRG GHVFULEHG E\ +\VORS   DQG %RZHQ ZKLFK DUH GRPLQDWHG E\ IRUHLJQ FRPPHUFLDO ÀVKHUV  ,QJHVWHGLWHPVZHUHFODVVLÀHGDVGHWULWXVSODQW predominantly from Mali and Nigeria, the middle material, insects (both adult and larval forms), aquatic 1\RQJULYHUÀVKHU\LVDWUDGLWLRQDOVXEVLVWHQFHÀVKHU\ crustaceans (primarily Macrobrachium VSS  RU ÀVK operated by the indigenous population; and, 2) much 'DWD ZHUH UHFRUGHG DV D SHUFHQWDJH RI IXOO VWRPDFKV of the southern portion of the middle Nyong basin containing one or more item from each food category ZKHUHRXUVDPSOLQJZDVFRQFHQWUDWHG GUDLQVVHDVRQDO UHSUHVHQWHG6WDWLVWLFD  VRIWZDUHZDVXVHGWR VZDPSIRUHVW D FULWLFDO VSDZQLQJ KDELWDW IRU PDQ\ SHUIRUPFOXVWHUDQDO\VLVWRLGHQWLI\PDMRUIRRGJURXSV UDLQIRUHVWULYHUÀVKHV 7KH6FKRHQHULQGH[ 6,  6FKRHQHU ZDVXVHGDVDQ indicator of dietary overlap among species.

Smithiana Bulletin 11: 3 - 16 &RPPHUFLDOÀVKHU\RIPLGGOH1\RQJ5LYHU&DPHURXQ 

Table 2./LVWRINQRZQLQGLJHQRXVVSHFLHVLQWKH1\RQJ5LYHU H[FOXGLQJWKRVHZLWKPDULQHDI¿QLW\ )LVKFDSWXUHG LQWKLVVWXG\DUHVKRZQLQEROGIRQW)LVKVSHFLHVQRWFDSWXUHGEXWUHSRUWHGLQWKHUHIHUHQFHFROOHFWLRQVRI the Royal Museum for Central Africa (RMAC), Tervuren, Belgium and/or the Muséum National de l’Histoire 1DWXUHOOH3DULVRU)LVK%DVH  DUHVKRZQLQQRUPDOIRQW6SHFLHVRQHZRXOGH[SHFWWRKDYHFROOHFWHGEXW which did not appear in our samples are indicated with a question mark (?).

5 February 2010 8 BRUMMETT ET AL.

Table 3.)LVKLQJWHFKQLTXHVDQGWKHVSHFLHVWKH\WDUJHWLQWKHPLGGOH1\RQJ5LYHU&DPHURRQ

Smithiana Bulletin 11: 3 - 16 &RPPHUFLDOÀVKHU\RIPLGGOH1\RQJ5LYHU&DPHURXQ 9

/XWMDQLGDH 3RO\QHPLGDH 6FLDHQLGDH DQG 6FRPEULGDH SPECIES DIVERSITY ZHUHFROOHFWHGIURPÀVKHUV·FDWFKHV Of the 83 species on the MRAC and MNHN lists, ZHUHUHFDSWXUHGLQ² 7DEOH ,QDGGLWLRQ In total, 15 families, 38 genera and 56 indigenous species VSHFLHVFDSWXUHGLQ²ZHUHQRWSUHYLRXVO\ ZHUHUHFRUGHG 7DEOH 2IWKHVHRQO\ LQFOXGLQJ on the list (Alestes macrophthalmus, Bostrychus africanus, WZR DOLHQ VSHFLHV Heterotis niloticus and Orochromis Brycinus longipinnis, Brycinus nurse, Chrysichthys niloticus) are currently important in the commercial auratus, Distichodus notospilus, Doumea ´&DPHURRQµ, catch. H. niloticus and O. niloticus are indigenous to the Mastacembelus cryptacanthus, Microsynodontis batesii, 1LJHU5LYHUDQG/DNH&KDGEDVLQVDQGZHUHVWRFNHG Nannocharax cf rubrolabiatus, Parailia occidentalis, and/or escaped from aquaculture facilities in the Paramormyrops curvifrons, Parananochromis ´1WHPµ 1\RQJZDWHUVKHGLQWKHODWHVDQGHDUO\VDQG Phractura longicauda, Schilbe intermedius, Synodontis KDYHVLQFHEHFRPHHVWDEOLVKHG 'HSLHUUH 9LYLHQ marmoratus & Varicorhinus sandersi) bringing the total Welcomme 1988). WR,QFOXGLQJWKHWZRDOLHQVWKHFXUUHQWOLVWLQFOXGHV +XJXHQ\  UHSRUWHGH[FOXVLYHO\IUHVKZDWHU 98 species. species in the collections of the MRAC, the French Every effort, including visits to MNHN, MRAC Muséum National d’Histoire Naturelle (MNHN) and DQGWKH$01+DQGH[WHQVLYHFRQVXOWDWLRQVZLWKRWKHU the Natural History Museum, London (BMNH). On WD[RQRPLVWVZDVPDGHWRXSGDWHDQGFRUUHFWWD[RQRPLF the list of Nyong River species held at the MRAC errors and changes on the list. Four errors (Micralestes DORQH WKHUH DUH  VSHFLHV -RV 6QRHNV 05$& SHUV humilis, Paramormyrops sphekodes, Parananochromis comm., Jan. 2004). At the MNHN in Paris, there are an caudifasciatus and Parauchenoglanis guttatus  ZHUH DGGLWLRQDOVSHFLHVQRWRQWKH05$&OLVWPDNLQJD IRXQG RQ WKH RULJLQDO OLVWV 6WLDVVQ\ HW DO   DQG WRWDORI '3DXJ\01+1SHUVRQDOFRPPXQLFDWLRQ FRQVLGHULQJWKHXQFHUWDLQW\VXUURXQGLQJWKHÀVKIDXQD 2FWREHU   ,Q FRQWUDVW 7HXJHOV  *XpJDQ   of the region others undoubtedly persist. Nevertheless, UHFRUGHG  VSHFLHV $OWKRXJK 7HXJHOV DQG *XpJDQ WKHUH UHPDLQV D VXEVWDQWLDO GLVFUHSDQF\ EHWZHHQ WKH did not present a list of species, a large part of the species caught in the 2001–2006 survey and those difference in count is probably due to their inclusion reported to be in the river by earlier observers. RI HXU\KDOLQH ÀVKHV ZKLFK FDQ PDNH XS DV PXFK DV $VWKHSULQFLSDOPHWKRGRIVDPSOLQJZDVEDVHGRQ ²RIWKHÀVKIDXQDLQWKHORZHUUHDFKHVRI$IULFDQ WKHJHDUVXVHGLQWKHFRPPHUFLDOÀVKHU\LWFRXOGEHWKDW FRDVWDOULYHUV 'MDPD7HXJHOV5HLG .LQJ  gear selectivity accounts for some of this discrepancy. ,QDEULHIYLVLWPDGHWRWKHORZHU1\RQJLQ0D\ Fishers tend to concentrate their effort on the main representatives of several typically marine families, i.e. river and do not target very small species. Although a Carangidae, Clupeidae, Cynoglossidae, Haemulidae, QXPEHURIVPDOOHUDQGUDUHUVSHFLHVZHUHWDNHQRIWKH

Fig. 4. 0RQWKO\FDWFKE\VSHFLHVJURXSLQ¿YHYLOODJHVRIWKH0LGGOH1\RQJ5LYHU%DVLQLQ

5 February 2010 10 BRUMMETT ET AL.

ÀVKRQWKHFRPELQHGOLVW 7DEOH WKDWZHUHQRWFDXJKW LQ²VSHFLHVVHOGRPH[FHHGFPLQWRWDO THE FISHERY OHQJWK DQG ZHUH JHQHUDOO\ XQNQRZQ WR ORFDO ÀVKHUV LQWHUYLHZHG DQG VKRZQ SKRWRJUDSKV ,Q DGGLWLRQ UHFOXVLYH RU SUHGRPLQDQWO\ VZDPS VSHFLHV VXFK DV The main gears used in the middle Nyong basin are Malapterurus electricus and Mastacembelus niger might VKRZQLQ7DEOH7KHODUJHDPRXQWRIDOORFKWKRQRXV EH H[SHFWHG WR EH LQIUHTXHQWO\ FDSWXUHG LQ D ÀVKHU\ ZRRGDQGERXOGHUVLQWKHVWUHDPEHGFRQVWUDLQVWKHXVH IRFXVHGRQWKHPDLQULYHUFKDQQHOV+RZHYHUVDPSOLQJ RIDFWLYHÀVKLQJJHDUV7UDGLWLRQDOLQGLJHQRXVPHWKRGV LQWHQVLW\ RU JHDUV DORQH FDQQRW H[SODLQ ZK\ VRPH UHO\RQGDPVEDVNHWWUDSVDQGYDULRXVKRRNOLQHV*LOO VSHFLHV ZHUH QRW UHFDSWXUHG DV PDQ\ RI WKH PLVVLQJ nets, introduced more recently, are the dominant gear species are very similar in size and shape to the species XVHGE\IXOOWLPHÀVKHUV WKDWZHUHFDSWXUHGDQGH[WUDVSHFLHVZHUHDGGHGWR Fishers can be differentiated as professional/ those on the earlier lists. IXOOWLPH PRVW RI ZKRP DUH 0DOLDQV EDVHG LQ WKH WRZQV RI 0EDOPD\R DQG $NRQROLQJD DQG ZKR WDUJHW Heterotis niloticus RUVHDVRQDOÀVKHUV7KHPDMRULW\DUH VHDVRQDOÀVKLQJDVSDUWRIDGLYHUVHOLYHOLKRRGVWUDWHJ\ WKDW LQFOXGHV KXQWLQJ VPDOO OLYHVWRFN DQG ERWK FDVK DQG IRRG FURSV 2I WKH  ÀVKHUV SDUWLFLSDWLQJ LQ WKH  FDWFK VXUYH\ VHYHQ   ZHUH IXOOWLPH DQG WKH UHVW ZHUH VHDVRQDO 2Q DYHUDJH ÀVKHUV ÀVK DERXWGD\VSHU\HDU IXOOWLPHÀVKHUVÀVKDERXW GD\VHDFKZKLOHVHDVRQDOÀVKHUVÀVKDERXWGD\V  FDSWXULQJDQDYHUDJHRINJRIÀVK )LJ &DWFK per unit of effort (CPUE) in the area sampled is thus NJÀVKHUÀVKLQJGD\$YHUDJHYLOODJHVHOOLQJSULFH IRUIUHVKÀVKLVIFIDSHUNJ DSSUR[LPDWHO\86 LQ ÀVKLQJKRXVHKROGVWKXVJURVVDQDYHUDJHRI VRPHWKLQJ RQ WKH RUGHU RI IFID  PLOOLRQ DQQXDOO\ IURP ÀVKLQJ LQFOXGLQJ KRXVHKROG FRQVXPSWLRQ QRW measured in this study), compared to the Cameroonian average gross income of fcfa 585,000 reported by the :RUOG %DQN LQ  KWWSGHYGDWDZRUOGEDQNRUJ $$*FPUBDDJSGI  Fig. 5.&DWFKFRPSRVLWLRQIURPDVXUYH\RI¿YH Leaving out the large urban centers of Mbalmayo villages in the middle Nyong River basin in and Yaoundé, the population density in the middle   1\RQJ %DVLQ LV HVWLPDWHG DW  SHUVRQV SHU NP2

Fig. 6. $¿VKGDPRUDODP FRQVWUXFWHGRQWKH)DOD5LYHU a tributary of the So’o in the central Nyong watershed. )LVKPLJUDWLQJXSVWUHDPWR spawn pass over the dam which is submerged at high water. As water levels GURSDGXOW¿VKUHWXUQLQJ from the spawning grounds are trapped, while smaller individuals pass through. Inset shows a detail of the FKXWHZKHUH¿VKDUHVWUDQGHG (Photo: R E Brummett.)

Smithiana Bulletin 11: 3 - 16 &RPPHUFLDOÀVKHU\RIPLGGOH1\RQJ5LYHU&DPHURXQ 11

A

B

Fig. 7. Seasonal variation in water clarity in the Nyong River basin. During the dry season (A), water is clear. )ROORZLQJUDLQV % H[SRVXUH of soil in the watershed due to logging, farming and associated road construction results in increased silt loads. (Photo: R E Brummett.)

(VVDPD1VVDK *RFNRZVNL VSUHDGRYHU survey conducted in October-December 2000 (Mdaihli NP2 RIWKHHQWLUH1\RQJEDVLQ ,IÀVKLQJSUDFWLFHV et al. 2003). LQWKHÀYHYLOODJHVDQGFDWFKHVLQWKHVXUYH\ 7KHPDLQÀVKLQJVHDVRQLVIURP6HSWHPEHUWKURXJK can be considered representative, about 40,000 full-time 'HFHPEHUZKHQULYHUOHYHOVDUHLQFUHDVLQJ )LJ DQG ÀVKHUV FDWFK DQ HVWLPDWHG  W RI ÀVK SHU DQQXP PDQ\VSHFLHVDUHXQGHUWDNLQJXSVWUHDPPLJUDWLRQVLQWR IURPWKHPLGGOH1\RQJ5LYHUÀVKHU\ WNP2 or 25 ÁRRGHGVZDPSIRUHVWWRVSDZQ 0XQURet al. 1990). A NJKD RI ZDWHUVKHG  VRPHZKDW KLJKHU WKDQ FDWFKHV VHFRQGSHDNRFFXUVLQ$SULO0D\$WRWDORIVSHFLHV RINJKDRIZDWHUVKHGLQWKHXSSHU&URVV5LYHUD ZHUHUHFRUGHGLQWKHSURIHVVLRQDOFDWFKWKHEXONRIWKH system similar to the Nyong, estimated from a frame FDWFK LV FODULLG FDWÀVKHV DQG Parachanna obscura (Fig.

5 February 2010 12 BRUMMETT ET AL.

5). Fishers reported that catches have remained more or less steady over recent years, in some cases actually LQFUHDVLQJ ZLWK WKH DYDLODELOLW\ RI JLOOQHWWLQJDQGÀVKKRRNV$OWKRXJK QRW\HWKDYLQJDPDMRULPSDFWRQWKH ÀVKFDWFKHVRIWKHYLOODJHVVDPSOHG

&DPHURRQ 7/ 7RWDO &DPHURRQ 7/ LQ WKH PLGGOH 1\RQJ ÀVKHUV PRUH generally report a gradual shift in emphasis from indigenous species to the introduced O. niloticus and H. niloticus since their introduction DW $NRQROLQJD LQ WKH HDUO\ V 'HSLHUUH 9LYLHQ$ELQD 

MISSING SPECIES

'HVSLWH JHDU VHOHFWLYLW\  VSHFLHV ZHUH QRW FDSWXUHG LQ ² although they reach commercial sizes and are found in the same KDELWDWV DV WKRVH VSHFLHV ZKLFK ZHUH FDSWXUHG 7KHVH LQFOXGH species of Clarias, Chrysichthys, Labeo, Labeobarbus, Mormyrops, Parauchenoglanis, Sarotherodon, Schilbe, Synodontis and Varicorhinus, VRPHRIZKLFKUHDFKVL]HVRI!FP DQGZHLJKWV!NJDQGZKLFKZHUH previously reported as important FRPSRQHQWV RI WKH ÀVKHU\ E\

RIVSHFLHVRI¿VKPRVWFRPPRQO\FDSWXUHGLQWKH1\RQJ5LYHU 'HSLHUUH  9LYLHQ   :KHQ SUHVHQWHGZLWKDOLVWDQGSKRWRVRI WKHPLVVLQJVSHFLHVÀVKHUVUHSRUWHG that Labeo annectens, Labeobarbus batesii, Labeobarbus micronema and Synodontis rebeli LQ SDUWLFXODU ZHUH much more common in the past. 'XULQJ $XJXVW RQH RI WKH SHDN ÀVKLQJ VHDVRQV  RI  D WZR ZHHNH[SHGLWLRQRIHLJKWÀVKHUVDQG WZR RI WKH DXWKRUV ÀVKHG WKH DUHD EHWZHHQWKHFRQÁXHQFHRIWKH6R·R 5LYHU DQG WKH WRZQ RI 0EDOPD\R VSHFLÀFDOO\ WR FDSWXUH WKH PLVVLQJ species. Using every traditional ÀVKLQJ PHWKRG VKRZQ LQ 7DEOH  Barbus guirali, Clariallabes longicauda and Paramormyrops curvifrons, SUHYLRXVO\ PLVVLQJ ZHUH DGGHG WR the list, but none of the other missing VSHFLHVZHUHFDSWXUHG In recent years, substantial KDELWDWPRGLÀFDWLRQDVVRFLDWHGZLWK rural development in the Nyong 3HUFHQWDJHRFFXUUHQFHRIGLIIHUHQWIRRGLWHPVLQWKHVWRPDFKV Basin, could have affected species ZKLFK ZHUH RQFH DEXQGDQW $ELQD Length ± Standard Deviation). 2005). Observation of the Nyong Table 4. Table

Smithiana Bulletin 11: 3 - 16 &RPPHUFLDOÀVKHU\RIPLGGOH1\RQJ5LYHU&DPHURXQ 13

Table 5.6FKRHQHULQGH[ 6, RIGLHWDU\RYHUODSIRUFRPPHUFLDOO\LPSRUWDQW¿VKVSHFLHVIURPWKH1\RQJ5LYHU Cameroon. Values for the introduced alien species Oreochromis niloticus  DQGHeterotis niloticus (17) are in EROGIRQW Brycinus macrolepidotus Brycinus kingsleyae Hemichromis elongates Oreochromis niloticus Clarias camerunensis Chrysichthys nigrodigitatus Anaspidoglanis macrostoma  Parauchenoglanis longiceps Labeo lukulae Raimas batesii Hepsetus odoe Brienomyrus brachyistius Marcusenius moorii Mormyrus tapirus Parachanna obscura Petrocephalus simus Heterotis niloticus Schilbe intermedius.

River during sampling revealed periodic substantial WKH 1\RQJ DW $NRQROLQJD LQ DQ HIIRUW WR HVWDEOLVK GHFOLQHV LQ ZDWHU TXDOLW\ HVSHFLDOO\ LQFUHDVLQJ D FRPPHUFLDO ÀVKHU\ 'HSLHUUH  9LYLHQ   ,Q sediment loads, as a result of human activities in the 'HSLHUUH 9LYLHQHVWLPDWHGWRIH. niloticus IRUHVW )LJ   7KHVH GHFOLQHV DUH SDUWLFXODUO\ VHYHUH captured in the vicinity of Ayos in the upper Nyong. ZKHQVRPHRIWKHPRVWFRPPHUFLDOO\LPSRUWDQWVSHFLHV (1984) estimated the H. niloticus catch landed DUHDFFRUGLQJWRWKHÀVKHUVXQGHUWDNLQJUHSURGXFWLYH DW $NRQROLQJD DW  W\HDU $ELQD   FDOFXODWHG migrations: early in the rainy seasons of March-June that Oreochromis niloticus accidentally introduced (Brycinus, Chrysichthys, Labeo, Labeobarbus, Marcusenius) LQWR WKH ULYHU IURP ÁRRGHG JRYHUQPHQW ÀVK SRQGV and September-November (Brienomyrus, Petrocephalus). DOVRDW$NRQROLQJDQRZUHSUHVHQWVRIWKHWRWDO According to Munro et al. (1990), Schilbe, Synodontis, catch in the upper Nyong basin. As their populations Clarias, Distichodus and Alestes are other important FRQWLQXH WR H[SDQG GRZQVWUHDP WKH LQWURGXFHG O. VSHFLHVUHSRUWHGWRVSDZQLQWKHZHWVHDVRQVDQGPD\ niloticus and H. niloticus FRXOGEHH[SHFWHGWRGLVSODFH thus be vulnerable to sedimentation during early life indigenous species (Lever 1996). In addition, after the VWDJHV,QXQGLVWXUEHGVLWHVZDWHUZDVFOHDUEURZQZLWK HQGRIIRUPDOVDPSOLQJÀVKHUVLQ3RQW6R·RFDSWXUHG DPHDQWHPSHUDWXUHRIƒGLVVROYHGR[\JHQEHWZHHQ D VSHFLHV WKH\ KDG QHYHU VHHQ EHIRUH ZKLFK XSRQ 4.2 and 6.5 mg/L (measured at noon) and electrical LQVSHFWLRQ ZDV LGHQWLÀHG DV Claris gariepinus, another FRQGXFWLYLW\EHWZHHQDQGPS/cm. In sites affected introduced species. Kamdem-Toham & Teugels (1998, E\ORJJLQJWKHZDWHUZDVFORXG\WRPXGG\ZLWKDPHDQ 1999) and Mdaihli et al.  VKRZHGKRZWKHFROOHFWLYH WHPSHUDWXUHRIƒGLVVROYHGR[\JHQRI PJ/DQG impact of introduced species, increased turbidity and average electrical conductivity of 48 PS/cm. the poisoning of streams have altered the ecological The use of pesticides such as Lindane, Thiosulfan structure of the Cross and N’tem Rivers in Southern  DQG *DPPDOLQ  IRU DJULFXOWXUH DQG ÀVKLQJ DQG 6( &DPHURRQ DQG LW VHHPV OLNHO\ VXFK FKDQJHV LV ZLGHVSUHDG LQ WKH PLGGOH 1\RQJ EDVLQ 7KHVH PD\OLNHZLVHEHQHJDWLYHO\DIIHFWLQJWKH1\RQJ5LYHU FKHPLFDOVNLOOYLUWXDOO\DOODTXDWLFIDXQDWRDGHSWKRI several centimetres into the mud and have long-lasting DIETARY CHARACTERISATION QHJDWLYHHIIHFWVRQÀVKGLYHUVLW\ GX)HX )LVKHUV UHSRUW WKDW VWUHDP VHFWLRQV ÀVKHG ZLWK SRLVRQV PD\ UHPDLQGHYRLGRIÀVKIRUXSWR\HDUV )LVK GLHWV 7DEOH   UHÁHFW WKH IRRG UHVRXUFHV RI WKH ,Q   ÀQJHUOLQJ Heterotis niloticus ZHUH UDLQIRUHVWULYHUHQYLURQPHQW/RZOLJKWDQGDONDOLQLW\ introduced by the Cameroonian Forestry Service to OLPLWWKHJURZWKRISK\WRSODQNWRQXSRQZKLFKPDQ\

5 February 2010 14 BRUMMETT ET AL.

WURSLFDO HFRV\VWHPV UHO\ DV WKH EDVLV RI WKH IRRG ZHE Indeed, the detritus/plant diet of the indigenous L. (Delincé 1992). The main nutrient inputs to rainforest lukulae VLJQLÀFDQWO\ RYHUODSV ZLWK RQO\ WKHVH WZR rivers such as the Nyong, are comprised mainly of species and L. lukulae is one of the species reported OHDYHVDQGRWKHUSODQWPDWHULDOVWKDWIDOORUDUHÁXVKHG E\ ÀVKHUV WR EH LQ GHFOLQH 2I WKH RWKHU JHQHUD DOVR LQ GXULQJ UDLQ RU ÁRRGLQJ HYHQWV :HOFRPPH  GH VSHFLÀFDOO\ UHSRUWHG WR EH GHFUHDVLQJ LQ DEXQGDQFH Merona 1988). The nutritional value of these decaying Clarias, Chrysichthys, Labeo, Labeobarbus, Mormyrops, plant materials derives primarily from the protozoa Parauchenoglanis, Sarotherodon, Schilbe, Synodontis and DQG EDFWHULD WKDW FRORQLVH WKHP $QGHUVRQ  Varicorhinus have all been reported to rely heavily on 0RULDUW\ DQGLQVHFWV SULPDULO\ODUYDOIRUPV DQG GHWULWXV DQGRU SODQW PDWHULDO DV PDMRU FRPSRQHQWV crustacean (primarily Macrobrachium spp) shredders of the diet (Matthes 1964; Seegers 1996). Cases of DQG JUD]HUV WKDW DUH LQ WXUQ FRQVXPHG E\ ÀVKHV competition for food having negative impacts on :ROIJDQJ -XQN 0D[ 3ODQN ,QVWLWXWH RI /LPQRORJ\ LQGLJHQRXV VSHFLHV KDYH EHHQ REVHUYHG HOVHZKHUH pers. comm., February 2003). 'HFOHUFNet al DQGDOWKRXJKOLWWOHLVNQRZQRIWKH &OXVWHU DQDO\VLV LGHQWLÀHG IRXU JURXSV EDVHG ecological impacts of H. niloticus introductions, cases of RQ GLHW *URXS $ Brycinus macrolepidotus, Brycinus FRPSHWLWLRQIRUIRRGDPRQJLQGLJHQRXVÀVKHVDQGO. kingsleyae, Chrysichthys nigrodigitatus, Anaspidoglanis niloticus resulting in declines in the former have been macrostoma, Parauchenoglanis longiceps & Schilbe ZLGHO\UHSRUWHG /HYHU  intermedius) eat mostly insects and/or aquatic crustacea. 'HSLHUUH 9LYLHQLQHVWLPDWHGWKHDQQXDOFDWFK *URXS% Clarias, camerunensis, Brienomyrus brachyistius, of H. niloticusDWWÀVKHUIRUDQDYHUDJHSURGXFWLYLW\ Marcusenius moorii, Mormyrus tapirus & Petrocephalus RINJKDRIZDWHUVXUIDFHDUHDLQWKHXSSHU1\RQJ simus WDUJHWLQVHFWVDQGFUXVWDFHDQVDVZHOOEXWLQFOXGH D ÁRRGSODLQ  &DWFKHV LQ WKH &URVV 5LYHU EDVLQ D D ODUJHU SURSRUWLRQ RI GHWULWXV LQ WKH GLHW *URXS & similar rainforest river ecosystem to the Nyong, are (Hemichromis elongatus, Raimas batesii, Hepsetus odoe & DERXWNJKDZDWHUVKHG 0GDLKOLHWDO DQGLW Parachanna obscura  DUH ODUJHO\ SLVFLYRUHV *URXS ' VHHPVXQOLNHO\WKDWWKHUHSRUWHGTXDQWLW\RILQWURGXFHG (Oreochromis niloticus, Labeo lukulae & Heterotis niloticus) ÀVKFRXOGEHJURZLQJLQWKHULYHUZLWKRXWDIIHFWLQJWKH depend heavily on detritus and aquatic plants. IRRGZHEDQGLQGLJHQRXVVSHFLHVLQVRPHZD\ Dietary overlap (Table 5) among species ZDV VLJQLÀFDQW ZLWK  RI  VSHFLHV KDYLQJ DQ average SI of at least the 0.6 considered as biologically &21&/86,216 VLJQLÀFDQW :DOODFH  5DPVH\   ,QVHFWV DQG DTXDWLF FUXVWDFHD ZHUH WKH PRVW RIWHQ WDUJHWHG IRRG 6LJQLÀFDQWFKDQJHVLQWKH1\RQJ5LYHUEDVLQRYHUWKH items overall, and those species that depend heavily ODVW\HDUVLQFOXGHORFDOLVHGGHIRUHVWDWLRQH[SDQGLQJ RQWKHVHJURXSVVKRZHGWKHKLJKHVWGHJUHHVRIGLHWDU\ VODVKDQGEXUQ DJULFXOWXUH ZLGHVSUHDG XVH RI LOOHJDO overlap. FKHPLFDO ÀVKLQJ DQG WKH LQWURGXFWLRQ RI DOLHQ ÀVK The large degree of feeding niche overlap among VSHFLHV :LWKRXW TXDQWLWDWLYH GDWD RQ SUHH[LVWLQJ VSHFLHVLVFRQVLVWHQWZLWKWKHÀQGLQJVRI0DWWKHV   FRQGLWLRQVDQGÀVKDEXQGDQFHLWLVLPSRVVLEOHWRVD\ ZKR VWXGLHG WKH PLGGOH &RQJR 5LYHU DQG +LFNOH\  for certain that these changes have resulted in the %DLOH\  ZRUNLQJRQWKH1LOHLQ6XGDQ)LVKFDQ GHFOLQHVLQLQGLJHQRXVVSHFLHVUHSRUWHGE\ORFDOÀVKHUV use spatial and/or temporal partitioning to minimise Nevertheless, the inability of researchers to recapture competition both among species and age-classes many once-common species indicates that some 0DWWKHV  .DQGHP7RKDP  7HXJHOV  negative changes have occurred. Similar ecological Brummett 2000). Although detailed behavioural and GLVWXUEDQFHV HOVHZKHUH KDYH UHVXOWHG LQ VLPLODU ecological niche data are unavailable, the relatively high GHFOLQHVLQLQGLJHQRXVVSHFLHVWKXVLWVHHPVOLNHO\WKDW indigenous biodiversity of rainforest rivers (Teugels & recent changes in the Nyong River basin have had a *XpJDQ   WKHLU DQWLTXLW\ 0DOH\  6FKZDUW] VLJQLÀFDQWQHJDWLYHLPSDFWRQDTXDWLFELRGLYHUVLW\ 1991) and the high level of dietary overlap, imply a FRPSOH[ RI EHKDYLRXUV UHJXODWLQJ DQG EDODQFLQJ WKH ecosystem. $&.12:/('*(0(176 7KH UHODWLYHO\ ORZ GHJUHH RI GLHWDU\ RYHUODS EHWZHHQ WKH LQWURGXFHG H. niloticus and O. niloticus 7KLVZRUNZDVFRIXQGHGE\WKH:RUOG)LVK&HQWHUDQG and indigenous species implies that these aliens are the British Department for International Development HLWKHU WDNLQJ DGYDQWDJH RI DQ XQGHUXWLOLVHG QLFKH RU through their Development of Integrated Aquaculture KDYH DOUHDG\ HOLPLQDWHG WKRVH VSHFLHV ZLWK ZKLFK Systems for Smallscale Farmers in the Forest Margins they compete. Without dietary data on the missing RI &DPHURRQ SURMHFW NRE9800 605/522/003. Special VSHFLHVLWLVSUHPDWXUHWRDVVXPHWKDWVXFKZKROHVDOH WKDQNVWR-RV6QRHNV'RPLQLTXH$GULDHQV(PPDQXHO UHGXFWLRQ LQ VSHFLHV GLYHUVLW\ DV LV EHLQJ ZLWQHVVHG 9UHYHQDQGWKHODWH*X\7HXJHOVDWWKH05$&'LGLHU LQWKH1\RQJ5LYHUFRXOGEHDWWULEXWHGH[FOXVLYHO\WR Paugy of the MNHN and to Melanie Stiassney of the GLHWDU\ FRPSHWLWLRQ ZLWK WKH LQWURGXFHG O. niloticus $01+IRUWKHLULQYDOXDEOHKHOSLQLGHQWLI\LQJWKHÀVK and H. niloticus, but some effect cannot be ruled out. and compiling the list of species.

Smithiana Bulletin 11: 3 - 16 &RPPHUFLDOÀVKHU\RIPLGGOH1\RQJ5LYHU&DPHURXQ 15

GARMAN, G.C. & J.R. MORING. 1993. Diet and annual /,7(5$785(&,7(' SURGXFWLRQ RI WZR ERUHDO ULYHU ÀVKHV IROORZLQJ clearcut logging. Environmental Biology of Fishes 36: ABINA, J-C. 2005. Characterisation de L’écologie du Basin 301–311. Versant du Fleuve Nyong. MSc Thesis, University GEERINCKX, T., D. ADRIAENS, G.G. TEUGELS & W. VERRAES. of Dschang, Cameroon.  $ V\VWHPDWLF UHYLVLRQ RI WKH $IULFDQ FDWÀVK ANDERSON, J.M.3URGXFWLRQDQGGHFRPSRVLWLRQLQ genus Parauchenoglanis (Siluriformes: Claroteidae). aquatic ecosystems and implications for aquaculture. Journal of Natural History 38² In: Detritus and Microbial Ecology in Aquaculture, HICKLEY, P & R.G. BAILY.  )RRG DQG IHHGLQJ HGV '-: 0RULDUW\  569 3XOOLQ SS ² UHODWLRQVKLSVRIÀVKLQWKH6XGGVZDPSV 5LYHU1LOH ICLARM Conference Proceedings 14, WorldFish southen Sudan). Journal of Fish Biology 30² Centre, Penang, Malaysia. HUGUENY, B. 1989. West African rivers as biogeographic BOWEN, S.H. 1983. Quantitative description of the diet. LVODQGV VSHFLHV ULFKQHVV RI ÀVK FRPPXQLWLHV In: Fisheries Techniques, eds. L.A. Nielsen & D.L. Oecologia 79: 236–243. Johnson, pp. 325–336. American Fisheries Society, HUGUENY, B. & C. LÉVÊQUE.  )UHVKZDWHU ÀVK Bethesda, Maryland, USA. zoogeography in West Africa: faunal similarities BRUMMETT, R.E. 2000. Food organism production and EHWZHHQULYHUEDVLQVEnvironmental Biology of Fishes resource partitioning in organically or inorganically 39: 365–380. fertilized Tilapia rendalli ponds. Aquaculture 183: HYSLOP E.J.6WRPDFKFRQWHQWVDQDO\VLVDUHYLHZRI ² methods and their application. Journal of Fish Biology BRUMMETT, R.E. & G.G. TEUGELS. 2004. Rainforest rivers 17: 411–429. of Central Africa: biogeography and sustainable KANDEM TOHAM A. & G.G. TEUGELS.  3DWWHUQV RI H[SORLWDWLRQ In: Proceedings of the Second PLFURKDELWDW XVH DPRQJ IRXUWHHQ DEXQGDQW ÀVKHV International Symposium on the Management of RIWKHORZHU1WHP5LYHU%DVLQ &DPHURRQ Aquatic Large Rivers for Fisheries, eds. R. Welcomme & T. Living Resources 10: 289–298. 3HWUSS²5$3)RRG $JULFXOWXUH KAMDEM-TOHAM A. & TEUGELS G.G. 1998. Diversity 2UJDQL]DWLRQ RI WKH 8QLWHG 1DWLRQV %DQJNRN SDWWHUQV RI ÀVK DVVHPEODJHV LQ WKH /RZHU 1WHP Thailand. 5LYHU %DVLQ &DPHURRQ  ZLWK QRWHV RQ SRWHQWLDO BURNS J.W.6RPHHIIHFWVRIORJJLQJDQGDVVRFLDWHG effects of deforestation. Archives of Hydrobiology road construction on northern California streams. 141(4): 421–446. Transactions of the American Fisheries Society 101² KAMDEM-TOHAM A. & TEUGELS G.G. 1999. First data DAGET, J. 1984. Contribution à la faune du Cameroun: RQ DQ LQGH[ RI ELRWLF LQWHJULW\ ,%,  EDVHG RQ ÀVK SRLVVRQV GHV ÁHXYHV F{WLHUV Bulletin du Muséum assemblages for the assessment of the impact of National de l’Histoire Naturelle de Paris 6² deforestation in a tropical West African river system. DECLERCK, S., G. LOUETTE,T.DE BIE & L. DE MEESTER. 2002. Hydrobiologia ² 3DWWHUQV RI GLHW RYHUODS EHWZHHQ SRSXODWLRQV RI LEVER, C. 1996. 1DWXUDOL]HÀVKHVRIWKHZRUOG. Academic QRQLQGLJHQRXVDQGQDWLYHÀVKHVLQVKDOORZSRQGV Press, London. Journal of Fish Biology 61² MALEY J.)UDJPHQWDWLRQGHODIRUrWGHQVHKXPLGHHW DELINCÉ, G. 1992. The Ecology of the Fish Pond Ecosystem, H[WHQVLRQGHVELRWRSHVPRQWDJQDUGVDX4XDWHUQDLUH with Special Reference to Africa. .OXZHU $FDGHPLF récent. Palaeoecology of Africa 18² Dordrecht, The Netherlands. MATTHES, H. 1964. Les Poissons du Lac Tumba et de la DEPIERRE, D. & J. VIVIEN.8QHUpXVVLWHGXVHUYLFH Région d'Ikela ; Etude Systématique et Ecologique. forestier du Cameroun: l’introduction d’Heterotis $QQDOHV6pULH6FLHQFHV=RRORJLTXHV0XVpH niloticus dans le Nyong. Revue Bois et Forêts Tropiques Royal de l’Afrique Centrale, Tervuren, Belgium. 173: 59–68. MBEGA, J.-D. & G.G. TEUGELS. 2003. Guide de Détermination DOUGLAS, I., T. GREER, K. BIDIN & M. SPILSBURY. 1993. des Poissons du Bassin Inférieur de l’Ogooué. Institut de Impacts of rainforest logging on rivers systems and 5HFKHUFKHV$JURQRPLTXHHW)RUHVWLqUHV/LEUHYLOOH communities in Malaysia and Kalimantan. Global *DERQ Ecology & Biogeography Letters 3: 242–252. MDAIHLI, M., T. DU FEU & J.S.O. AYENI. 2003. Fisheries DJAMA,T.)LVKELRGLYHUVLW\LQYHQWRU\RIWKHORZHU LQ WKH VRXWKHUQ ERUGHU ]RQH RI 7DNDPDQGD )RUHVW 1WHP 5LYHU *()&DPSR0D·DQ 3URMHFW )LQDO Reserve, Cameroon. In: Takamanda: Biodiversity of Report, Kribi, Cameroon. an African Rainforest HGV -$ &RPLVNH\ 7&+ DU FEU, T.A. 2001. Fish and Fisheries in the Southern zone of 6XQGHUODQG -/6XQGHUODQG*URYHVSS the Takamanda Forest Reserve, SW Cameroon. Report to Smithsonian Institution Monitoring and Assessment WKH&DPHURRQLDQ*HUPDQ3URMHFWIRUWKH3URWHFWLRQ of Biodiversity Program, Washington, DC. RI)RUHVWVDURXQG$NZD\D*7=&DPHURRQ MENGANG,M.1984. La Pêche de l’Heterotis niloticus sur ESSAMA-NSSAH, B. & J.J. GOCKOWSKI. 2000. Cameroon Forest le Nyong Secteur -Djoudjoua. Mémoire du 6HFWRU 'HYHORSPHQW LQ D 'LIÀFXOW 3ROLWLFDO (FRQRP\ 'LSO{PH8QLYHUVLW\RI'VFKDQJ&DPHURRQ 7KH:RUOG%DQN:DVKLQJWRQ'& MORIARTY,D.  0HWKRGRORJ\ IRU GHWHUPLQLQJ

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