Catch and distribution of bycatch species and discards from Spanish tropical purse-seine fishery

Transcription

1 IOTC-27-WPEB- Cach and disribuion of bycach species and discards from Spanish ropical purse-seine fishery by Delgado de Molina, Alicia; Javier Ariz; J.Carlos Sanana and Robero Sarralde ABSTRACT This documen presens resuls abou una discards, and he cach and disribuion of several groups of fauna species associaed wih free schools and floaing objecs. The daa analysed correspond o hose obained from 34 rips wih observers of he Spanish Oceanographic Insiue. A oal of 14 days and 863 ses were underaken in he presence of observers. Daa (in weigh) for una caches, discards and bycach, separaed according fishing mode and year, for he Spanish ropical purse-seine flee beween 23 and 26, are included. KEYWORDS Indian Ocean, ropical una, discards, purse-seine, discards, floaing objecs, bycach. Page 1 of 14

2 Inroducion The European ropical purse-seine una flee operaing in he Alanic and Indian Oceans provides exremely valuable informaion abou is fishing aciviy hrough fishing logs, which are compleed along wih samplings in por. This informaion is exclusively direced a commercial una caches. However, his flee discards arge species as well as several species of bycach. These daa can only be obained from observers on board. Sysemaic daa collecion by scienific observers in he European purse-seine flee in he Indian Ocean is included in he Naional Daabase Plan (PNBD). This documen presens resuls abou una discards, and he cach and disribuion of several groups of fauna species associaed wih free una schools and paricularly wih floaing objecs (s). Maerial and mehods The daa analysed correspond o hose obained from 21 rips wih observers from he Naional Daabase Plan of he Spanish Oceanographic Insiue (PNDB-IEO), financed by he EU and carried ou beween 23 and 26, and 13 rips underaken wihin a Pilo Projec financed by he Secrearía General de Pesca Maríima Española (Spanish General Secrearia of Mariime Fisheries) in collaboraion wih a shipowning company. A oal of 14 days and 863 ses were underaken in he presence of observers. We considered five groups for he daa regarding accompanying fauna: billfishes, sharks, urles, oher fishes and ceaceans. There were no caches for he laer group, and, consequenly, no menion is made in ables or graphs. Daa have been grouped according o fishing mode (objec and free school). The coverage was no ideal for oally reliable exrapolaions, bu we believe ha curren coverage provides a closer view of discard and bycach daa. For he aforemenioned exrapolaions, we considered he number of ses performed by he Spanish purse-seine flee per fishing mode (objec and free school) and year. Resuls Table 1 shows he number of ses, per fishing mode and oal, underaken wih observers on board beween 23 and 26, while Table 2 conains he number of ses, per per fishing mode and oal, underaken by he Spanish ropical purse-seine flee operaing in he Indian Ocean beween 23 and 26. Table 3 presens daa (in ons) for una caches, discards and bycach, separaed according o fishing mode and year, for he Spanish ropical purse-seine flee beween 23 and 26. These daa are graphically represened in Figure 1. The ons corresponding o he commercial cach, discard and bycach for objec and free school are shown o he lef of his figure. The commercial cach has been omied o he righ of his figure in order o appreciae he oher wo groups in greaer deail. Figure 2 gives he raio of bycach species, per fishing mode, underaken by he flee beween 23 and 26. We observed ha here is specific variabiliy beween he differen years considered. Skipjack is he species wih he highes rae of discards for fishing over objecs for he enire period considered, excep for one year, when i was frigae una. There is more variabiliy for free school han for objec. Figure 3 shows he discards (in ons) per species, for objec and free school, for each year considered. s are seen o be normally much higher over objecs han over free schools, wih values varying beween 12 ons (23) and 2347 ons (24) over free schools, and beween 89 ons (2) and 4194 ons (24) over objecs. Skipjack is he species wih mos discards, followed by frigae una. Figure 4 presens he proporion, in weigh, of he differen groups of fauna (excluding urles), per fishing mode and year. We observed ha he Oher Fishes group is he mos imporan in fishing over objecs, since he proporion varied beween 7% and 8% according o year. This was followed by sharks (beween 33% and 17%) and by swordfish (beween 4% and 14%). By far he dominan group, over free schools are sharks, excep for he las year considered, when swordfish were he highes cach. Page 2 of 14 2

3 Figure shows he differen groups of fauna lised according o he main species in each group, separaed by fishing mode, bu grouped for he enire period considered. Table 4 gives he number of urles caugh, per fishing mode, during he IEO observer campaigns beween 23 and 26 in he Indian Ocean, while Figure 6 shows he raio, in numbers, of he various urle species per fishing mode. This has no been exrapolaed o he fishery in he case of he urles. Table included all he species of bycach, disinguishing beween hose caugh over floaing objecs and hose over free schools. Figure 7 presens siuaions of ses over floaing objecs, in which some of he groups of fauna appeared in he following order (from op o boom and from lef o righ): swordfish (group 1), Selachii (group 2), Oher Fishes (group 3) and urles (group 4). Figure 8 shows he same over free schools. Figure 9 corresponds o he disribuion of swordfish caches (lef objec and righ free school). Figures 1, 11 and 12 correspond o Selachii, he firs for his enire group separaed per mode of fishing; 11 shows sharks o he lef and rays o he righ (in boh cases, caches were made over floaing objecs); while 12 presens hese same groups over free schools. Figure 13 corresponds o he disribuion of caches of Oher Fishes (lef, objec, and righ, free school). The caches of hese hree groups (swordfish, Selachii and oher fishes) are in ons. Figure 14 shows caches (in numbers) of urles: on he lef of he figure, over objecs, and on he righ, over free schools. Page 3 of 14 3

4 Table 1. Number of ses per fishing mode and oal underaken wih observers beween 23 and 26. Toal Observer Ses Toal Table 2. Number of ses per fishing mode and oal underaken by he Spanish ropical purse-seine flee operaing in he Indian Ocean beween 23 and 26. Toal Fishery Ses Toal Table 3. Cach (in ons) of una, discards and bycach per fishing mode and oal for he Spanish ropical purse-seine flee operaing in he Indian Ocean beween 23 and 26. Toal Fishery 23 Tuna caches s Toal Toal Fishery 24 Tuna caches s Toal Toal Fishery 2 Tuna caches s Toal Toal Fishery 26 Tuna caches s Toal Page 4 of 14 4

5 Table 4. Number of urles caugh per fishing mode during he IEO observer campaigns underaken beween 23 and 26 in he Indian Ocean. Turles Observers' daa Table. Lis of species of associaed fauna, presen or oherwise, according o mode of fishing. Associaed fauna % Free school % s BILLFISHES Isiophoridae family x x Isiophorus playperus x x Makaira indica x x Terapurus angusirosris x x Terapurus audax - x Xiphias gladius - x OTHER FISHES Ablennesse hians - x Abudefduf vaigiensis x - Acanhocybium solandri x x Aluerus monoceros - x Aluerus scripus x x Canhidermis maculaus x x Carangoides orhogrammus - x Carangoides orhogrammus - x Caranx crysos - x Caranx sexfasciaus - x Coryphaena equiselis - x Coryphaena hippurus x x Decaperus macarellus - x Diodon hysrix x x Elagais bipinnulaa x x Balisidae family - x Belonidae family x x Bramidae family x x Carangidae family x x Coryphaenidae family x x Diodonidae family x - Echeneidae family x x Ephippidae family - x Exocoeidae family x - Fisularidae family x - Molidae family x - Pomacenridae family - x Teraodonidae family - x Kyphosus cinerascens - x Kyphosus secaor x x Kyphosus sp. - x Kyphosus vaigiensis - x Lagocephalus lagocephalus x - Loboes surinamensis x x Naucraes ducor x x Page of 14

6 Oher unidenified fish x - Plaax sp. - x Plaax eira - x Remora ausralis - x Remora remora x x Remorina albescens - x Ruveus preiosus - x Seriola rivoliana - x Sphyraena barracuda x x Tylosurus crocodilus - x Uraspis helvola - x Uraspis secunda x x Uraspis sp. - x Zanclus cornuus x - SHARKS Carcharhinus falciformis x x Carcharhinus longimanus x x Carcharhinidae family x - Dasyaidae family x x Sphyrnidae family - x Isurus oxyrinchus - x Mana birosris x x Mobula mobular x - Mobula sp x - Mobula arapacana - x Prionace glauca x - Peroplayrygon violacea x x Rhincodon ypus x x Sphyrna lewini x - TURTLES Carea carea - x Chelonia mydas - x Eremochelys imbricaa - x Lepidochelis kempii - x Lepidochelis olivacea - x Page 6 of 14 6

7 23 Fishery daa 23 Fishery daa Cach Fishery daa 24 Fishery daa Cach Fishery daa 2 Fishery daa Cach Fishery daa 26 Fishery daa Cach 1 1 Figure 1. Caches, discards and fauna (in ons), per fishing mode, for he Spanish ropical purse-seine flee beween 23 and 26 (lef). Caches have been omied on he righ of he figure. Page 7 of 14 7

8 Species Proporion 23. FRI 2% YFT 4% Species Proporion 23. BET FRI % % YFT 33% SKJ 4% SKJ 62% Species Proporion 24. YFT SKJ 7% % Species Proporion 24. E.affinis % YFT 4% FRI 37% SKJ 4% FRI 93% BET % Species Proporion 2. FRI 49% YFT 3% Species Proporion 2. YFT 6% SKJ 2% BET 1% SKJ 11% FRI 67% BET 2% Species Proporion 26. YFT SKJ % 6% Species Proporion 26. YFT 18% E.affinis 8% FRI 36% FRI 3% BET 4% SKJ 43% Figure 2. Proporion of discard species, per fishing mode, for he Spanish ropical purse-seine flee operaing in he Indian Ocean beween 23 and 26. Page 8 of 14 8

9 Toal discard PS Spanish Fishery objeo libre YFT SKJ BET FRI E.affinis Toal discard PS Spanish Fishery YFT SKJ BET FRI E.affinis objeo libre Toal discard PS Spanish Fishery objeo libre 1 YFT SKJ BET FRI E.affinis Toal discard PS Spanish Fishery objeo libre YFT SKJ BET FRI E.affinis Figure 3. s, per species and fishing mode, underaken by he Spanish ropical purse-seine flee beween 23 and 26. Page 9 of 14 9

10 s % Oher fishes 4% 1% 23% Oher fishes 63% 9% s % Oher fishes 12% 1% Oher fishes 8% 33% 78% s 2 2 8% Oher fishes 2% 4% 17% Oher fishes 7% 94% s % 24% Oher fishes 32% 46% Oher fishes 72% 22% Figure 4. Proporion in weigh of he various groups of fauna (excluding urles), per fishing mode, beween 23 and 26. Page 1 of 14 1

11 STM 23% WHM 1% SWO 1% BLM 19% SHS 11% SPF 1% SHS 1% BMM 6% SAP 19% BLM 4% SAP 3% SAI % FIS 7% BUM 38% FIS 8% BMM 17% Oh. 8% Oh. 7% CFA 19% CLO 23% MOM 36% CLO 16% CFA 69% MBA 22% Oher Fishes Oher Fishes WAH 12% Oh. 6% BCM 19% Oh. 9% COH 28% CLM 8% ELP 42% COH 13% ELP 63% Figure. Proporion (in weigh) of he main species wihin each group of fauna (excluding urles) per fishing mode beween 23 and 26. Turles Turles TOX 2% CCC 11% LOL 36% CMM 2% DCC 2% CMM % CCC % LKE 7% EIM 22% Figure 6. Proporion in numbers of he differen species of urles per fishing mode for he period Page 11 of 14 11

12 fauna all obj gr fauna all obj gr fauna all obj gr fauna all obj gr Figure 7. Disribuion of ses over objecs where some groups of fauna appeared in he following order (from op o boom and from lef o righ): swordfish (group 1), Selachii (group 2), oher fishes (group 3) and urles (group 4) fauna all lib gr fauna all lib gr fauna all lib gr fauna all lib gr Figure 8. Disribuion of ses over free school where some groups of fauna appeared in he following order (from op o boom and from lef o righ): swordfish (group 1), Selachii (group 2), oher fishes (group 3) and urles (group 4). Page 12 of 14 12

13 fauna all obj gr fauna all lib gr1 1. Figure 9. Map of caches of swordfish species over objecs (lef) and free school (righ) fauna all obj gr fauna all lib gr2 1. Figure 1. Map of caches of Selachii over objecs (lef) and free school (righ) fauna all obj gr fauna all obj gr22 1. Figure 11. Map of disribuion of shark (lef) and ray (righ) caches over objecs fauna all lib gr fauna all lib gr22 1. Figure 12. Map of disribuion of shark (lef) and ray (righ) caches over free schools. Page 13 of 14 13

14 fauna all obj gr fauna all lib gr3 1. Figure 13. Map of caches of oher fishes over objecs (lef) and free school (righ) fauna all obj gr fauna all lib gr4 1. Figure 14. Map of caches of urles over objecs (lef) and free school (righ). Page 14 of 14 14