CEPHALOPOD PREY OF THE APEX PREDATOR GUILD IN THE EPIPELAGIC EASTERN PACIFIC OCEAN FELIPE GALVAN-MAGAÑA1 ROBERT J. OLSON 2 NOEMI BOCANEGRA-CASTILLO1 VANESSA GUADALUPE ALATORRE- RAMÍREZ 1 1Centro Interdisciplinario de Ciencias Marinas (CICIMAR) 2Inter-American Tropical Tuna Commission OVERVIEW Sharks,Sharks, billfishes,billfishes, tunas,tunas, dolphinsdolphins andand mahimahi--mahimahi areare thethe mainmain predatorspredators onon cephalopodscephalopods inin thethe EasternEastern PacificPacific waterswaters (Perrin(Perrin etet al.al. 1973;1973; GalvanGalvan etet al.al. 1985,1989;1985,1989; AbitiaAbitia--CárdenasCárdenas etet al.al. 1997,1998,1997,1998, 1999,1999, 2001;Aguilar2001;Aguilar 1998,1998, MarkaidaMarkaida andand SosaSosa 1998;1998; GalvanGalvan 1999.1999. OlsonOlson andand GalvanGalvan 2002;2002; RosasRosas--AlayolaAlayola etet al.al. 2002)2002) .. TheThe stomachstomach contentscontents ofof thesethese predatorspredators permitpermit toto knowknow thethe distributiondistribution andand abundanceabundance ofof cephalopods,cephalopods, consideringconsidering thethe difficultydifficulty toto catchcatch themthem withwith traditionaltraditional methods.methods. PelagicPelagic predatorspredators havehave shownshown toto bebe thethe mostmost effectiveeffective cephalopodcephalopod samplers,samplers, consideringconsidering theirtheir sizesize mouthmouth andand velocityvelocity theythey cancan capturecapture cephalopodscephalopods ofof allall sizes.sizes. OneOne ofof thethe mainmain problemsproblems toto analyzeanalyze thethe stomachstomach contentscontents inin largelarge predatorspredators isis thethe advancedadvanced digestiondigestion statestate foundfound inin prey.prey. InIn cephalopods,cephalopods, thethe mandiblesmandibles (beaks)(beaks) areare thethe mostmost frequentfrequent structurestructure foundfound inin thethe stomachs,stomachs, becausebecause theirtheir chemicalchemical compositioncomposition isis chitin,chitin, whichwhich isis moremore resistantresistant toto predatorspredators gastricgastric acids.acids. METHODS TWOTWO DATADATA BASEBASE WEREWERE USEDUSED TOTO ANALYZEANALYZE THETHE INFORMATIONINFORMATION ONON CEPHALOPODSCEPHALOPODS ININ THETHE EASTERNEASTERN PACIFICPACIFIC OCEAN:OCEAN: 19921992--19941994 .. IATTCIATTC PROJECT.PROJECT. TOTO FOUNDFOUND THETHE RELATIONSHIPRELATIONSHIP BETWEENBETWEEN YELLOWFINYELLOWFIN TUNATUNA ANDAND DOLPHINSDOLPHINS ININ THETHE EASTERNEASTERN PACIFICPACIFIC OCEAN.OCEAN. PURSEPURSE--SEINERSSEINERS FROMFROM PANAMA,PANAMA, VENEZUELAVENEZUELA ANDAND MEXICO.MEXICO. 1992-1994 (IATTC PROJECT) 35 Dolphin sets 30 Schoolfish Log sets 25 20 15 10 5 0 -5 -10 -15 -145 -140 -135 -130 -125 -120 -115 -110 -105 -100 -95 -90 -85 -80 -75 Predator Number Spotted dolphin Stenella attenuata 311 manchado Stenella longirostris Spinner dolphin 209 Delphinus delphis Common Dolphin 51 Stenella coeruleoalba Striped dolphin 5 Thunnus albacares Yellowfin tuna 4831 Katsuwonus pelamis Skipjack tuna 1205 Thunnus obesus Bigeye tuna 80 Euthynnus lineatus Black skipjack 100 Auxis spp. Bullet tuna 55 Carcharhinus limbatus Black tip shark 262 Carcharhinus falciformis Silky shark 64 1994-1995 Carcharhinus longimanus Whitetip shark 30 Carcharhinus leucas Bull shark 2 Carcharhinus spp. Other carcharhinids 82 Sphyrna spp. Hammerhead shark 48 Isurus oxyrinchus Mako shark 4 Prionace glauca Blue shark 2 Alopias spp. Thresher shark 12 Nasolamia velox Whitenose sharka 2 Makaira indica Black marlin 25 Makaira mazara Blue marlin 15 Makaira spp. Marlins 18 Tetrapturus audax Striped marlin 8 Istiophorus platypterus Sailfish 49 Coryphaena hippurus Mahi-mahi 545 Acanthocybium solandri Wahoo 235 Elagatis bippinulata Rainbow-runner 48 Total 8298 20032003--2005.2005. PFRPPFRP PROJECT.PROJECT. STABLESTABLE ISOTOPESISOTOPES ANDAND FEEDINGFEEDING HABITSHABITS OFOF PREDATORSPREDATORS ININ THETHE EQUATORIALEQUATORIAL PACIFICPACIFIC OCEAN.OCEAN. PURSEPURSE--SEINERSSEINERS FROMFROM ECUADORECUADOR ANDAND MEXICO.MEXICO. 2003-2005 (PFRP PROJECT) 35 Schoolfish Dolphin sets 30 Log sets 25 20 15 10 5 0 -5 -10 -15 -145 -140 -135 -130 -125 -120 -115 -110 -105 -100 -95 -90 -85 -80 -75 PREDATOR NUMBER PREDATOR NUMBER Alopias pelagicus 3 Auxis rocheii. 12 Carcharhinus 290 Auxis thazard 8 falciformis C. limbatus 5 Euthynnus lineatus 37 C. longimanus 4 Katsuwonus 310 pelamis Isurus oxyrinchus 2 Thunus albacares 937 Sphyrna spp. 1 Thunnus obesus 82 Sphyrna zygaena 3 Thunnus orientalis 7 2003-2005 Sphyraena ensis 2 Stenella attenuata 1 Sphyraena spp. 2 Stenella 1 longirostris Kiphosus elegans 18 Uraspis helvola 2 Kiphosus analogus 10 Seriola lalandi 3 Kiphosus spp. 2 Seriola rivoliana 46 Makaira nigricans 14 Elagatis 171 bipinnulata Istiophorus 1 Decapterus 23 platypterus macarelus Tetrapturus audax 1 Caranx 8 sexfasciatum Tetrapturus 1 Caranx spp. 11 angustirostris Acanthocybium 417 Aluterus monoceros 8 solandrii Lobotes pacificus 18 Aluterus scriptus 9 Corypahena 291 Balistes polylepis 1 hippurus C. equiselis 4 Canthidermis 92 maculatus TOTAL 2 488 90% 80% 70% Yellowfin tuna 60% 50% 40% % occurrence30% 20% 10% 0% Argonauta spp. Teuthoidea Dosidicus gigas Sthenoteuthis oualaniensis Crustacea Exocoetidae Carangidae Scombridae Nomeidae Tetraodontiformes 2003-2005 Other fishes 1992-1994 90% 80% 70% Bigeye tuna 60% 50% 40% % occurrence30% 20% 10% 0% Argonauta spp. Teuthoidea Dosidicus gigas Sthenoteuthis oualaniensis Crustacea Exocoetidae Carangidae Scombridae Nomeidae Tetraodontiformes 2003-2005 Other fishes 1992-1994 90% 80% 70% 60% Sharks 50% 40% % occurrence30% 20% 10% 0% Argonauta spp. Teuthoidea Dosidicus gigas Sthenoteuthis oualaniensis Crustacea Exocoetidae Carangidae Scombridae Nomeidae Tetraodontiformes 2003-2005 Other fishes 1992-1994 90% 80% 70% Billfishes 60% 50% 40% % occurrence30% 20% 10% 0% Argonauta spp. Teuthoidea Dosidicus gigas Sthenoteuthis oualaniensis Crustacea Exocoetidae Carangidae Scombridae Nomeidae Tetraodontiformes 2003-2005 Other fishes 1992-1994 90% 80% 70% Wahoo 60% 50% 40% % occurrence30% 20% 10% 0% Argonauta spp. Teuthoidea Dosidicus gigas Sthenoteuthis oualaniensis Crustacea Exocoetidae Carangidae Scombridae Nomeidae Tetraodontiformes Other fishes 1992-1994 90% 80% 70% Rainbow runner 60% 50% 40% % occurrence30% 20% 10% 0% Argonauta spp. Teuthoidea Dosidicus gigas Sthenoteuthis oualaniensis Crustacea Exocoetidae Carangidae Scombridae Nomeidae Tetraodontiformes 2003-2005 Other fishes 1992-1994 90% 80% 70% Dolphinfish 60% 50% 40% % occurrence30% 20% 10% 0% Argonauta spp. Teuthoidea Dosidicus gigas Sthenoteuthis oualaniensis Crustacea Exocoetidae Carangidae Scombridae Nomeidae Tetraodontiformes 2003-2005 Other fishes 1992-1994 %Number 10 20 30 40 50 60 70 80 0 Abraliopsis falco Abraliopsis spp Alloposus mollis Ancistrocheirus lesueuri Argonauta cornutus Argonauta nouryi Argonauta spp Dosidicus gigas Alloposidae Loliginidae Ommastrephidae Japetella diaphana Loligo opalescens Yellowfin tuna L.diomedeae Mastigoteuthis dentata Mastigoteuthis spp. o. Octopoda o. Teuthoidea Octopoteuthis deletron Octopus rubescens Octopus spp Onichoteuthis spp Onychoteuthis banksii Pholidoteuthis boschmai Stenoteuthis oualaniensis Thysanoteuthis rhombus Tremoctopus violaceus Vampyroteuthis infernalis Vitreledonella richardi 1993-1995 2003-2005 % number 10 20 30 40 50 60 70 0 Argonauta spp. o. Teuthoidea Octopoteuthis deletron f. Thysanoteuthidae Thysanoteuthis rhombus f. Ommastrephidae Dosidicus gigas (92-94) DELFINES Sthenoteuthis oualaniensis Onychoteuthis spp. Onychoteuthis banksii Abraliopsis falco Abraliopsis spp. Mastigoteuthis spp. f. Loliginidae Tremoctopus violaceus Common dolphin (4) dolphin Common Spinner dolphin (16) dolphin Spinner Spotted dolphin (30) Spotted dolphin Striped dolphin (5) dolphin Striped 100% Mastigoteuthis spp. 80% Abraliopsis falco Onychoteuthis banksii Sthenoteuthis oualaniensis 60% Dosidicus gigas F.Ommastrephidae Thysanoteuthis rhombus Octopoteuthis deletron 40% o. Teuthoidea Japetella diaphana Argonauta nouryi 20% Argonauta spp. Octopus rubescens 2003 - 2005 0% 100% Sharks Tunas Billfish Dolphins Ancistrocheirus lesueuri Loliginidae 80% Mastigoteuthis dentata Pholidoteuthis boschmai Onychoteuthis banksii 1992 - 1994 60% Sthenoteuthis oualaniensis Dosidicus gigas Thysanoteuthis rhombus 40% o. Teuthoidea Japetella diaphana Argonauta spp 20% Argonauta cornutus Octopus rubescens 0% Sharks Tunas Dolphinfish Wahoo and billfish SHARKS (92-95) Tremoctopus violaceus 100% Liocranchia reinhardtii Alloposus mollis 80% Mastigoteuthis spp. Abraliopsis falco 60% Pholidoteuthis boschmani Onychoteuthis banksii 40% Sthenoteuthis oualaniensis Dosidicus gigas 20% f. Ommastrephidae Thysanoteuthis rhombus 0% Octopoteuthis deletron o. Teuthoidea Argonauta spp. Argonauta pacifica Thresher (4) Bull shark (2) shark Bull Silky shark (6) Silky shark SHARKS (2003-2005) hammerhead (7) hammerhead Shortfin mako (1) mako Shortfin Blacktip shark (21) shark Blacktip 100% Carcharhinus spp. Carcharhinus (10) Oceanic whitetip shark (2) shark whitetip Oceanic Smooth hammerhead (10) hammerhead Smooth 80% Ancistrocheirus lesueuri Onychoteuthis banksii Stenoteuthis oualaniensis 60% D.gigas o. Teuthoidea 40% Vitreledonella richardi Japetella diaphana Argonauta spp 20% Argonauta cornutus 0% (27) (1) (1) (2) Pelagic Smooth Silky shark Oceanic thresher (1) hammerhead whitetip shark whitetip Shortfin mako EPICEPHALOPODS 1992-1994 60 50 40 30 % number 20 Wahoo (114) 10 Dolphinfish and others (51) Tunas (306) Shark (30) 0 Loliginidae O. Teuthoidea Argonauta spp Dosidicus gigas Octopus rubescens Argonauta cornutus Onychoteuthis banksii Loliolopsis