size: 5036KB - Crocodile Specialist Group

More documents

Recommendations

Info

80 Sustainablc harvcsls were calculaled by rsking what level of change in I, or m, would convert an ircreasing populaiion to a slaiionary one, i.e. would mnkc c'= l Equation I is thcn solved for lhe new parameter value, for example, fof egg harvests, wherc q is lhe proporiion ofeggs collected, m. in equation I becomes (l 'q)m. at equilibrium, reananging thc equalion then gives: \-r n (craig 9! 4!. 1992). RT]SUI,TS AND DISCUSSION Given lhe pammeler values of Table 1, the polential rate of incrci$e for Nile crocodiles was estimatcd lo be e'= 1.08, i.e. an 87, annual rate of incre.se. Unceilxirly in the parametea used. however. result in npproximate conficence linits of e' = 1.03 lo e' = 1,13. The vast majority of uncert:inty (Column 4 of Table 1) in lhe value of c' appears to derive from pmr cslimatcs of three piuamctcn, namcly survivorship Io age l. survivorship from 1 lo maturily and ag€ at maturily. ClcaJly, if lhere is to bc ar improvement in otu ability lo make prediclions, future res€lrch must concentrale on obhining beller estimates of lhcse. Susmined yields of a variety of harvesling slralegieshow that egg collcclion xnd reffing to a <strong>size</strong> of 12 melres is superior to any other sIrxtegy. e.g. Txble 2 compares the yie,d o[ egg collection with crcpping animals lrom lhc wild direclly for skin. Table 2. Comparison of egg collection wilh cropping animals >1,2 metres STRATDCY SUSTAINABLE % TAKFN 9t% SKIN YIELD 218 There may be less differential economically between the slrategies of Table 2, because of the cost of hxrhing and rearing crocodiles. but in cons€rvalion terms. it is the absolute compxrison which is valid. The robustness ofegg collcction as a slralegy is also obvious from lhc pcrccnlagc of eggs it is permissible to collect. Such a high proportion collected would be unlikely to be achieved evcn if lhere were no restrictions on egg collection. This robushess bsromes even mo.e apparent when options involving replacement of juvcniles are investigated. Here the relum of 0,5% (of lhe number of collected eggs) as crocodiles rearcd to the length of l.2m resulls in reslonlion of sustainabilily even when all eggs are collecred (Gaig 9! 4., 1992). The simple model of crocodllc population dynamics describcd here enables somo useful conclusions to be drawn about safe harvesting slrategies. That these also seem inluilively acceptcbl€ is additionally encouraging.
81 REFERENCES Craig. G.C., D. Si.C. cibson and J.M. Hu(on 1989. A Modet ofrhe Crocodite popularion of Zimbabwe. Repon to the Branch of Torestrial Ecology, Dept. of Nationaj parks & Witdlife Management, Zmbabwe. Cmig, G.C.. D. Sl.C. Gibson and l.M. Hu(on 1992. A population rnodel for the Nile crocodrte and simulation of different harvesting stntegies.In: cITEs and the Nle crocodire in Eas/cenlral Alrica and Madagascaf. CITES Secretarial, Lausnnne. Switzcrland. Craham, A.D. 1968. The Lake Rudolf crocodite CIg!!{LUS niloticus hurenti) population. Msc thesis, Univcrsity of Nairobi, Kenya. Hutton, J.M. 1988. Thc population ecotogy of the Nilc cro€odile Crocodvtus niloricus hurend, t?68, at Lake Ngezi, Zimbabwe. D.Phil thesis. Unive.sity of Zimbibwe. Nichols. J.D., L. Viehman. R.H. Chrbreck and B. Fergerson 1976. Simulalion of a commercialtv hawested alligator popularion i0 Louisiana. Bulletir of the Louisiana State Univenity Agriculrur; Experimenl:rl Stnlion. 691: I , 59. Smith, A.M.A., and OJ.W. Webb t985. Crocodvtus iohnsloniin the McKinlay Rive. arca, N.T_ V[. A population simulation model. Austnlian Wildlife Research. l2: 551-557. Webb, GJ.W.. P.G. Bayliss and S.C. Mffolis 1989. popularion research in crocodiles in the Nonhem Ter.itory, 1984 - 86. Proceedi gs 8th working meering CSG. IUCN publ. (N.S.): 22_59.
Page 1 and 2:
CROCODILES Proc€€dings of the l
Page 3:
FOREWORD The two volumes of this PR
Page 6 and 7:
Elsey, R M, McNease, L & Joanen, T:
Page 9 and 10:
CFAZ CIIAIRMAN'S OPENING COMMENTS F
Page 11 and 12:
PRESENTATION FROM THE MINISTER OF E
Page 13 and 14:
Fitting Curves to crocodilian Aqe-s
Page 15 and 16:
7 a.set of uniforrn random nunbers.
Page 17 and 18:
2. VON BERTAI"ANFFY MODEL FOR GROWT
Page 19 and 20:
11 The -following four tables give
Page 21 and 22:
UNIFoRU sarnpling MEDfUM sahpl ing
Page 23 and 24:
15 Sectior IV: Actual Croc Data, l,
Page 25 and 26:
1'l (ii) Linear regressron. same ra
Page 27 and 28:
1,9 rejecting nufl hypotheses that
Page 29 and 30:
21 Brisbin, I.L., Jr., c.c. White,
Page 31 and 32:
Iength lthich corresponds to the ni
Page 33 and 34:
25 Because of lack of funds Eo carr
Page 35 and 36: 27 Despite the fact that during a p
Page 37 and 38: 29 FIGURE N9 2 BLACK CAIIIAN POPULA
Page 39 and 40: I'Effect of diets conplenented vith
Page 41 and 42: 3i Two of the 6 x 2 m. tanks four e
Page 43 and 44: : .i ; -3, E .-1 t FFdF !_9 + + + +
Page 45 and 46: 10 Table IV : fl aernathological Re
Page 47 and 48: 4l 4.- CONCLUSIoNS 1) The most favo
Page 49 and 50: 43 THE INVOLVEMENT OF RURAL COMMUNI
Page 51 and 52: 45 the rainy season and, in conhast
Page 53 and 54: 47 difficulties and the isolation o
Page 55 and 56: 49 Eacb time that one of the villag
Page 57 and 58: 51 CONCLUSION Naturally, these rcsu
Page 59 and 60: 53 LONG-TERM POPUT-A.TION S'ruDIES
Page 61 and 62: 55 'Ile study reporled here was des
Page 63 and 64: 5'7 made of transmilteFequjpped ndm
Page 65 and 66: 59 wilhin the reservoir was lypific
Page 67 and 68: 6l However the use of such winter d
Page 69 and 70: 6.1 surface to breathe (Kellogg 192
Page 71 and 72: 65 ACKNOWLEDGMENTS This work was su
Page 73 and 74: Murphy, T. M., P. M. Wilkinson, J-
Page 75 and 76: 69 t 3 ^ 3 :9s 3P o ;x !B 'rr.l9 3e
Page 77 and 78: 7l FoDd B + i Poud C I Pltllr. l. U
Page 79 and 80: 73 9 October 1991 L t' I L t' 26 Ma
Page 81 and 82: 75 80 -r- 1987-88 + 1991-92 t -40 .
Page 83 and 84: 77 GROWTH RAIE OF CAIMAN (Caiman cr
Page 85: 79 Values of the life lable paramet
Page 89 and 90: 83 CUMATIC F{w L Stirldi .6.aiDS EF
Page 91 and 92: 85 2. Behavioral facilitation of re
Page 93 and 94: 87 TeEperature, hy&ic coaditionq aa
Page 95 and 96: 89 The sexual behaviors of irdividu
Page 97 and 98: 9l 2o I E F conuor o.r r.0 r0.0 a0.
Page 99 and 100: 93 Referetrces Ber!, H.A. (1990). T
Page 101 and 102: 95 GROWTH RATES AND BODY CONDITION
Page 103 and 104: 97 LIPID AND FATTY ACID COMPOSMONAL
Page 105 and 106: 99 be removed sustalnably, provided
Page 107 and 108: 101 necessary as the endurance of t
Page 109 and 110: 103 Table 2. The ratio of first sig
Page 111 and 112: 105 3) Movement and dispersal The r
Page 113 and 114: 107 Disease Trend$ on Crocodite Far
Page 115 and 116: 109 Fuigol and other dermar,?ir - d
Page 117 and 118: 111 THE FEEDINC ECOLOGY OF TWO NILE
Page 119 and 120: 113 areas outside the National park
Page 121 and 122: 115 been done for a tlpical populat
Page 123 and 124: 117 ACKNOWLU)GEMENTS This study was
Page 125 and 126: 119 THE STATUS AN'D DISTRIBUTION OF
Page 127 and 128: Figure l: Crocodile Survey - Tanzan
Page 129 and 130: 123 :rD ES e € a 69 PE e 3 Er t !
Page 131 and 132: 125 Ruaha River (Figure 2) The Ruah
Page 133 and 134: 127 lake Mtera (Figure 4) This is a
Page 135 and 136: t29 with 6shermenand subsistence f'
Page 137 and 138:
lil Kilimmjaro/Tanga Region Pa gani
Page 139 and 140:
133 The numbers of crccodiles durin
Page 141 and 142:
135 REFERENCES Chabreck, R.H. 1966.
Page 143 and 144:
l -37' 3.1.4 lagal Trad.e Local tra
Page 145 and 146:
l.l9 In order to gecure credibility
Page 147 and 148:
l4l 'rould apply to 6kins of good h
Page 149 and 150:
143 This infdrrDation cduld be supp
Page 151 and 152:
l.l-s ].nternational reEplfnstbitit
Page 153 and 154:
t4'/ illegal sttjns in their pr,r,d
Page 155 and 156:
149 CROCODILE SKIN INDUSTRY IN ETII
Page 157 and 158:
l5l Table 2. Ouotas for Ethiopian c
Page 159 and 160:
153 depriving EWCO of incentive for
Page 161 and 162:
155 A PRELII{] NARY ASStsSS!.IENT O
Page 163 and 164:
15',7 Origin l Payert lltosk Breedi
Page 165 and 166:
159 dropped, producing 23 and l9 eg
Page 167 and 168:
l6l This figure ts even lorrer than
Page 169 and 170:
163 =z 3F \riciNoraj {
Page 171 and 172:
165 References EArr,ER, R.D. ( 1976
Page 173 and 174:
t6'1 IPPIIDIX tt BtoBtE cI0@(DILX n
Page 175 and 176:
l()t/ Backqround l,lelano5uchus nio
Page 177:
t7l The numbers of black cainan c'b
show all

size: 5036KB - Crocodile Specialist Group

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?