Tuesday, July 31, 2007

Sperm whales in Pico

Today we were lucky with our whale watching in Pico Island. We found a pod of sperm whales just one mile from the Ribeiras Village. The sea was calm the whales looked like logs floating over the surface. They were calmly resting with smooth movements, socialising amongst themselves every now and then. We just stopped the boat and spent some time queitly observing these moments.

Our trip got even better when we came across a pod of Atlantic spotted dolphins. They followed the boat, jumping and riding the waves as if they were surfing.

In the afternoon there was a lot of wind at sea but we were just as succesfull with the same two species: sperm whales and Atlantic spotted dolphins.

Whales Whales Whales!!!

Yes, sperm whales are here today, close to São Miguel Island! This month we have seen whales every single day. Today we have seen them again!
Morning tour:
During the morning trip we spotted sperm whales on south of the island, close to Vila Franca. On this tour we ha the incredible chance of witnessing the birth of a calf, a baby sperm whale. It was a tremendous moment with emotions and feelings shared by the crew and passengers alike!

The trip finished with a pod of common dolphins.
Afternoon tour:
Even with a bit of wind we were lucky again with plenty of sperm whales to see. Among the group we resighted the baby sperm whale that we saw being born this moring. The calf was like milky coffee, very different to the other whales that we saw in the area.

The whales were spotted by our vigia, a man on land looking for whales and dolphins with powerfull binoculars. It was difficult because the visibility was poor due to fog, but still he managed to find the whales for us!

The trip ended with a show of Atlantic spotted dolphins.

Late afternoon tour:
Today we had an extra third tour in the late afternoon. Unfortunately the visibility had deteriorated, causing our vigia and the boats in the whale area to loose sight of the whales. Nevertheless, a pod of common dolphins made every body happy after some time looking for the whales.

Whale lice fact sheet

Whale lice (cyamidae) are small crustaceans, not lice despite their name. The name "whale lice" comes from the whalers, as they often had lice (Pediculus sp.) themselves and they saw how there were lots of animals crawling all over the whales as on themselves. Whale lice are between 5-15 mm long and are grouped into 7 genera and 32 species. Many species are physically almost identical and for many years they were classified as one species. Many new discoveries are made all the time, the most recent was 1991. A lice species that used to be classified as Isocyamus deplhinii is now Isocyamus kogiae as they live on pygmy sperm whales (Kogia breviceps).

Domain           Eukaryota      
Kingdom         Animalia        
Phylum           Arthropoda    
Subphylum     Crustacea       
Class               Malacostraca       
Order              Amphipoda    
Suborder         Corophiidea
Infraorder       Caprellida
Family            Cyamidae      
Genera            Cyamus, Isocyamus,
  Neocyamus, Platycyamus,
  Scutocyamus, Sirenocyamus and Syncyamus

The hosts that carry whale lice are both baleen whales (mysticeti) such as right whales, grey whales and rorquals, and toothed whales (odontoceti) such sperm whales, beaked whales, dolphins, and porpoises.

Northern right whales, Eubalaena glacialis and Eubalaena japonica, always have the lice on the same spots: on the rostrum (bonnet), the chin (beard) and above the eyes (eyebrows). Sourthern right whales (Eubalaena australis) also have an edge around the lip which the Northern right whales are missing. The lice have small hooks to cling on to the whales' callosities, which are crusty growths made of the whale itself, barnacles and Caprellids amphipods. On the callosities there are about 5000 Cyamus ovalis which gives them the white color. Between the callosities there are about 200 lice of the species C. glacilis and adult animals have are bout 2000 lice (C. Erraticus) around the genetalia. One whale can have as many as 7,500 lice living on its skin. Cyamus ovalis, C. glacilis and C. erraticus are not three species but 9 species as the right whales (Atlantic right whale, pacific right whale and Southern right whale) have their own unique lice seperated into different species.

Whale lice feed on dead skin cells and dead skin of their host, and other things that get stuck on the whale such as algae, but they do not feed on the whale itself. It is not a real louse nor a parasite, more just a free-rider that cleans the whale. Some whale lice are filter-feeders and eat plankton that drift by the whale.

The whale lice reproduce on the whale. Most are amphipods that have free-swimming stage, but this is something whale lice are missing and the female keep her offsprings in a marsupium on her underside and the offsprings, when ready, crawl onto the whale. Whale lice move from one whale to the other via close contact between mother and calf, or male and female during mating. A newborn calf doesn’t have lice, they are transmitted from the mother. Otherwise the lice stays on the whale throughout its life.

Mutualism or parasitism? When it comes to the interaction between cyamidae and Northern right whales can be classified as somewhere in between mutualism and parasitism. The whale doesn’t really benefit from the lice but the lice gets great benefits and is building its entire life around the whale, it is dependent on the whales lifecycle for its survival. The whale get one way of help as it gets rid of dead skin and other parasites.

For the whale research, the lice is very informative. The lice has been sitting on the whales for miljons of years and followed the evolution of the whales. Research on the lice has given us many answers when it comes to the evolution; for 5-6 miljon years ago the right whale was divided into three species, Southern right whale, Atlantic right whale and Pacific right whale. One, of just a few, Southern right whales crossed the ekvator  for about 1-2 miljon years ago and spread their lice (C. ovalis) to the Pacific right whale. Researchers has found that the lice on the Pacific right whale is closer related to the Southern then the Atlantic. The Southern right whales that crossed the ekvator probably didn’t mate with the Pacific right whale as the C. erraticus, that lives around the genitalia is not affected. This is amazing though right whales can’t cross the ekvator because it is too warm, as they have to much blobber. Whale lice also help researchers to identify individual whales, and makes the research easier. All right whales are unique, but sometimes it is diffecult to tell some individuals apart though they don’t have nay whites pots and are completly black. Witht he help of the lice the whale turns unique in shape and color. Probably the lice is irritating the skin, but it helps the research, which can be seen as a benefit for the whales in the long run.

One reason whales are jumping is to get rid of parasites and lice. Pec-fin slapping and lobtailing can also be a way to get rid of lice. Many species of cetaceans also rubb their bodies against rocks and seabottom, even in captivity. Cetaceans can also get help from birds to get rid of parasites when they come to the surface to breathe.

When we come to the situation for the lice we see that they are in danger in the future, because many of the whales they are living on are endangered. Atlantic and Pacific right whales are endangerd, and the Southern right whale are at risk and in need of conservation. Grey whale populations are at risk, and one population became extinct in the 1700s. Other threatened species of baleen whales are blue whale, fin whale, sei whale, humpback whale, all four species of minke whale, pymgy right whale and bowhead whale. Other whale species at risk are the vaquita, indus river dolphin, irrawaddy dolphin, and different populations of dolphins in certain areas (such as orca, bottlenose dolphin, spinner dolphin, pantropical spotted dolphin, pilot whales and melonheaded whale), many beaked whales, sperm whale and kogids.
An action for conservation of cetaceans and keep healthy populations is very important for the whale lice survival. Even if one whale can carry 5000 lice, the less whales they have the more they are at risk for inbreeding. When there are no more whales, there are no more whale lice.

Some of the cyamidae is strictly living on one whale species, such as Cyamus catodontis that only lives on male sperm whales, and Neocyamus physeteris that only lives on sperm whale female and calves. But a few species are finding new hosts, and the Isocyamus deplhinii doesn’t only exist on the shortbeaked common dolphin, it has been discovered on 12 other toothed whales, such as Risso’s dolphins, shortfinned pilot whales and longfinnes pilot whales, whitebeaked dolphin, false orca, bottlenose dolphin, harbour porpoises, rough-toothed dolphin, Gervais beaked whale and orca. But, whale lice is not moving onto other species then cetaceans.

Worms can be seen on most cetaceans, and in the Azores we see these worms hanging from the fins of all dolphin species, and the baleen whales. On the minke whale we can see species as Pennella and Cocconeis ceticolaThe orcas seems to have a Xenobalanus sp.

Iceland gull fact sheet

Larus glaucoides | Iceland gull

The Iceland gull can be confused with the glaucous gull, but can be distinguishid by the projection of the primary wings, as they clearly extend beyond the tail (more pointed). They are also smaller and more compact in flight. They can reach a size of 52 - 64 cm, with a weight of 820 - 1100 g and a wingspan of 125 - 145 cm. Iceland gulls can live to be 33 years old and lay 1 - 3 eggs at a time, incubating them for 28 - 30 days. Fledging occurs about 40 - 45 days after hatching. The beak of adult Iceland gulls is yellow with a light green tone and a red mark on the distal part of their lower jaw. They have pink legs and feet. In the Azores Iceland gulls can be seen in the winter, but sightings are very rare. They breed in the Arctic regions of Canada and Greenland, and outside the breeding season they can they be found wintering in the USA, UK, Iceland, Ireland, Norway and other parts of Scandinavia and north of Germany. In the summer they mainly feed in fish, marine invertebrates, bird eggs and chicks, seeds, fruit. In the winter they often seen feeding on debris, in fishing ports and dumpsters. Their population is stable but they are locally hunted in Greenland.  

In other languages
Portuguese: Gaivota polar
Spanish: gaviota groenlandesa
French: Goéland arctique/Goéland à ailes blanches
Italian: Gabbiano d'Islanda
German: Polarmöwe
Dutch: Kleine burgemeester
Swedish: Vitvingad trut
Norwegian: Grønlandsmåse
Danish: Hvidvinget måge
Finnish: Grönlanninlokki
Polish: Mewa polarna
RussianПолярная чайка

Glaucous gull fact sheet

Larus hyperboreus | Glaucous gull

The glaucous gull is the second largest gull and occures rarely in the Azores. They can reach a length of 63 - 68 cm, with a weight of 1200 -2000 g and a wingspan of 142 - 162 cm. They can be seen from October to April, close to the coast (and in the marina of Ponta Delgada), and may be seen in large flocks with other gulls. Their large size is the best way to differenciate them from other gulls with similar plumage. They are very similar to the European herring gull, but with the upper wings a paler shade of grey. Glaucous gulls have a circumpolar distribution, with several subspecies distributed between the Arctic and Subarctic coasts and islands of Europe, Asia and America. Depending on the population, they can behave as a partial or totally migratory species, or be dispersive. They are active predators around nesting colonies of seabirds. Glaucous gulls can live to be 21 years old and they are omnivorous, feeding mainly on fish, eggs and young birds (and some garbage in winter time). They lay 2 - 3 eggs and incubate them for 27 - 28 days. fledging occurs around 49 days.

In other languages
Portuguese: Gaivotão branco
Spanish: Gavión hiperbóreo/gaviota hiperbórea
French: Goéland bourgmestre
Italian: Gabbiano glauco
German: Eismöwe
Dutch: Grote burgemeester
Swedish: Vittrut
Norwegian: Polarmåke
Danish: Gråmåge
Finnish: Isolokki 
Polish: Mewa blada

Sooty shearwater fact sheet

Ardenna griseus | Sooty shearwater

The sooty shearwater is a medium sized shearwater reaching a length of 40 -50 cm, with a weight of 650 - 950 g and a wingspan of 93 - 106 cm. They have a dark colouration with long, pointed wings. In low light they can appear black and in good light chocolate brown with a pale band on the underside of the wing center. The beak is dark and they feed on small fish, shrimps and other crustaceans, squid and jellyfish. They lay one egg at a time which is incubated for 53 days and fledging occurs after 97 days. Sooty shearwaters can live to be 34 years old. They can dive as deep as 68 m to catch fish and they often follow whales and dolphins. 

In other languages
Portuguese: Perdela preta
Spanish: Pardela sombría
French: Puffin fuligineux
Italian: Berta grigia
German: Dunkle Sturmtaucher
Dutch: Grauwe pijlstormvogel
Swedish: Grålira
Norwegian: Grålire
Danish: - 
Finnish: Nokiliitäjä

Polish: Burzyk szary
RussianСерый буревестник

Salps fact sheet

Salpa fusiformis Salps

Salp is the name given to a set of planktonic species of tunicates of the Salpidae family, characterized by gelatinous bodies of cylindrical shape. These bodies move longitudinally, pumping the water through their bodies while filtering with a set of internal lamellar structures which retain plankton, its only known food. Salps are common in most oceans, occuring surface waters of equatorial, subtropical, temperate and cold waters, both as isolated individuals or colonies that consist of long linear chains of connected individuals. Their life cycle has mandatory alternating forms between generations. They are sequential hermaphrodites, initially maturing as females, and then fertilized by male gametes produced by older chains. Both life cycle forms co-exist in seawater, and although they appear very different, both are generally transparent, tubular, soft, with dimensions which are usually between 1 and 10 cm long. The solitary forms, known as "oozóides" are small barrel-shaped animals that reproduce asexually, producing a chain of tens to hundreds of individuals released from the parent as submicroscopic beings. This species can often be confused with Salpa aspera. May be seen in the Azores, in significant quantities.

Length1- 10 cm

Diet: Plankton and other small particles

Reproduction: Sexual (hermaphrodites)

Conservation Status: There is not concern for this species

In other languages:
Portuguese: Salpa
Spanish: Sálpidos
French: Salpida
Italian: Salpe/salpida
German: Salpidae
Dutch: Salpidae
Swedish: Bandsalper
Norwegian: -
Danish: Salpe
Finnish: -
Polish: Salpida/salpy
Russian: Са́льпы

Moon jellyfish fact sheet

Aurelia auritaMoon jellyfish 

The moon jellyfish is a member of the escifozoos class of jellyfish and one of the most abundant and common in all the world's oceans, mainly in coastal areas. It has four (or 5 to 7 ) horse shoe-shaped gonads which are symmetrically arranged. In females the gonads, or "moons" are pink in colour, whereas in males they are white. Moon jellyfish feed on zooplankton and small invertebrates such as crustaceans, and polychaetes. They use their tentacles to capture and paralyse their victims and guide them up to the mouth. Moon jellyfish swim by contracting their body with regular undulations. They stay near the surface, often travelling adrift on currents. Sometimes they are found stranded on the coast in large numbers, as they are not good swimmers. Their sting generally does not bother humans.

Length: Diameter: 5 - 40 cm

Diet: Zooplankton such as molluscs, crustaceans, tunicate larvae, copepods, rotifers and nematodes.

Reproduction: Sexual and asexual. Sexes are separate

Maturity: 3 months to 2 years  (ephyra to sexually reproducing medusa)

Conservation Status: There is no concern for the conservation of this species

In other languages:
Portuguese: Medusa de lua
Spanish: Medusa común
French: Méduse commune
Italian: Medusa quadrifoglio
German: Ohrenqualle
Dutch: Oorkwal
Swedish: Öronmanet
Norwegian: Glassmanet
Danish: Vandman
Finnish: Korvamedusa
Polish: Chełbia modra
Russian: Ушастая аурелия

Mauve stinger fact sheet

Pelagica noctiluca | Mauve stinger 

The mauve stinger can be find widely distributed throughout the world's warm and temperate oceans. Their colour varies, ranging from pink to shades of golden yellow to tan. Most jellyfish have a complex life cycle that alternates between a free swimming (medusa) and bottom-living (polyp) phase. However, the mause stinger has adapted so there is only a free swimming medusa stage wich is either male or female. Male and female jellyfish reproduce sexually by releasing eggs and sperm, which devolop directly into young (male or female) jellyfish. They are usually found in the upper 150 m of the water column, but may be found as deep as 1,400 m. At night they may be seen to bioluminesce. In the Azores these jellyfish occur frequently during the summer months, both isolated and in loose or dense blooms. Mauve stingers can deliver a painful sting to humans.

Diameter: 3 - 12 cm
Tentacles: 3 m (maximum)

Diet: Pelagic ascidians, zooplankton such as salps and other smaller jellyfish

Reproduction: Sexual, males and females release eggs and sperm

Population: Unkown

Conservation Status: Atlantic stocks appear to be healthy

In other languages:
Portuguese: Áqua-viva
Spanish: Acalefo luminiscente
French: Méduse pélagique/piqueur-mauve
Italian: Medusa luminosa
German: Leuchtqualle
Dutch: Parelkwal/lichtende kwal
Swedish: Lysmanet
Norwegian: -
Danish: -
Finnish: Loistomeduusa
Polish: Meduza świecąca
Russian: -

Common remora fact sheet

Remora remoraCommon remora

The common remora is one of the six remora species (Family Echeneidae) that occurs in the Azores. Remoras have an elongated body and are characterised by having a modified first dorsal fin and a head in the form of a suction cup. This suction cup or disc on the top of the head permits the remora to attach to other animals such as sharks, mantas, turtles, whales and dolphins. They are even known to attach to the hull of boats. This type of relationship with a host is commensal, meaning that one (the remora) benefits without harming the other (the host animal). The remora benefits by aquiring protection and food from the host. Although the bond is strong, remoras can also temporarary swim free in the open ocean or in coastal areas. Remoras are found in warm waters up to depths of 100 m. Little is known about the reproductive biology, although reproductive couples are known to share the same host.

35 - 40 cm (max 86,4 cm)

On hosts:  food scraps, ectoparasites and exrement of the host;
Free-swimming animals: small fish and invertebrates

Population: Unkown

Conservation Status: Not evaluated

In other languages:
Portuguese: Rémora
Spanish: Rémora
French: Rémora
Italian: Remore
German: Schiffshalter
Dutch: Remoras/zuigbaarzen
Swedish: Sugfisk/remora fisk
Norwegian: Sugefisk
Danish: -
Finnish: Remorat
Polish: Podnawkowate
Russian:  Прилипаловые

Spotted dolphin juvenile with remora

Spotted dolphin juvenile with remora

Fin whale with a remora attached below its dorsal fin

A giant oceanic manta ray with a remora on top of its head

Velella fact sheet

Velella velella | Velella 

Velella is also know as the "by the wind sailor" or "Jack sail by the wind". A single velella  is actually a hydroid colony of numerous all-female polyps, each with one of three different specialised functions:

1) Feeding - a large tubular individual with a mouth  in the centre of colony (Gastrozoid)

2) Defense - several smaller individuals surrounding the feeding individual ( Dactylozooid)

3) Reproduction and Defense - the remaining individuals of the colony (Gonozooid)

The blue colour comes from a pigment, astaxantine, which protects the colony from sunlight. During the spring and autumn it is common to see large chains or aggregations of velellas known as blooms. Wind and currents can push these blooms so that mass strandings can occur on beaches. Although they use toxins to catch their prey, velellas are essentially harmless to humans.

Colony6 - 7 cm
Medusa: 1 mm

Diet: Crustaceans and fish larvae and eggs.

Reproduction: Bipartite life cycle with alternate asexual and sexually reproducing generations in the form of polyps and medusas respectively.

Population: Unknown

Conservation Status: Unknown

In other languages:
Portuguese: Velela
Spanish: Velella
French: Vélelle
Italian: Barchetta di San Pietro
German: Segelqualle
Dutch: Bezaantje
Swedish: Bidevindseglare
Norwegian: Bidevindseiler
Danish: Bidevindssejler
Finnish: Purjehtijamaneetti
Polish: -
Russian: Парусница

Tuna general fact sheet

Thunnus albacares | Yellowfin tuna

The yellowfin tuna can reach a maximum length of 3.2 m and a maximum weight of 190 kg. The yellowfin tuna can be identified at surface by the brilliant yellow colour of the second dorsal fin, which is more elongated than in other tuna species. They are migratory and pelagic and can be found in waters with depths of up to 800 m (although they pass the majority of their time in the upper 100 m of the water column). They may approach coastlines, but they are most often seen in open ocean and in the vicinity of seamounts. They are distributed throughout subtropical and tropical waters of the world, except in the Mediterranean. The time of spawning peaks during the summer months, with a single female releasing millions of eggs at a time (almost exclusively at night). This species is well known to gather with groups of dolphins during feeding frenzies. In the Azores, yellowfin tuna are normally seen between April and October. The local minimum catch limit is 3.2 kg. They feed on smaller pelagic fish, such as Atlantic chub mackerel, blue jack mackerel, boar fish and cephalopods (squid and octopus) in the Azores. Reproduction is oviparous with external fertilization (162,918 – 8,062,026 eggs per spawning) and they can live to be 8 years. Conservation status: Near Threatened. 

Thunnus thynnus | Bluefin tuna

The bluefin tuna reaches a length of 2 - 3 m (maximum 6.79 m) and weighs betweem 136 and 680 kg. The bluefin tuna is one of the most well adapted species of tuna in the world, and also the most appreciated by mankind. It's the largest species of tuna and can dive to about 914 m deep. It is estimated that bluefin tuna can reach speeds up to 50 km/h. This species is highly migratory and is homeothermic, meaning that it is capable of regulating its body temperatur relative to its enviroment. Bluefin tuna can be seen in more northern latitudes  than any other tuna species. During the reproductive period individuals group up in large schools, making them more vulnerable to overfishing. In the Azores, bluefin tuna occur year-round, but are more common from the end of March to the end of April, and occasionally from the end of September to the end of October. The individuals that occur in the Azores reproduce in the Mediterranean. Bluefin tuna feed on fish such as skipjack, Atlantic chub mackerel, herring, sea bass, flying fish, mullets, squid and eels. Reproduction is oviparous with external fertilization (spawning  up to 90 egg per gram of body weight (more then others in the genus Thunnus). They can live to be at least 35 years old but possibly up to 50 years (breeding age: Western Atlantic 8 - 12 years and Eastern Atlantic 3 - 5 years). Conservation: Endangered and declining.

Thunnus obesus | Bigeye tuna

The bigeye tuna can reach a maximum length of 2.39 m and weigh 30 – 130 (in the Azores) (maximum weight is 210 kg). The bigeye tuna has a metalic blue colouration on its dorsal and a white ventral. They can be distinguished from other tuna species by the presence of an irridescent blue longitudinal band and its eyes which are larger than in other tuna species. They occur in waters ranging from 13 - 29° C, with the ideal range 17 - 22° C, and can dive down to about 500 m deep. Bigeye tuna are distributed throughout the Atlantic, Pacific and Indian Oceans, but they do not occur in the Mediterranean. They prefer open ocean, but can also be in coastal waters, especially around oceanic banks and seamounts. Spawning can occur several months with a frequency of every day of second day. Bigeye tuna is highly valued  in the fishing industry and in the Azores it is the second most captured tuna species, after the skipjack tuna. In the Azores they may be found between April and October but are most abundant from mid April to mid June. Bigeye tuna feed on smaller pelagic fish, such as Atlantic chub mackerel, blue jack mackerel, boar fish and cephalopods (squid and octopus) in the Azores. Reproduction is oviparous with external fertilization (Average 2.9 – 6.3 million eggs/spawning). Longevity: Western pacific: 16 years, Indian Ocean: 8 years, Atlantic Ocean: 9 years, Eastern Pacific: 5 years. Conservation status: Vulnerable (population decreasing). 

Thunnus alalunga | Albacore

The albacore can reach a length of 1.2 – 1.4 m and weigh 40 – 60 kg. The albacore tuna, or simply albacore is characterised by having very long pectoral fins, leading to its name in portuguese "atum voador" which means "flying tuna". This species is known for its tireless fighting during the fishing season. They are found mostly in the upper 100 m of the water column, but can dive down to 800 m. Albacore inhabit tropical to subtropical regions with surface waters typically ranging from 15.6˚ C to 19.4˚ C, although they can tolerate temperatures as low as 9.5˚ C for short periods. This species is highly migratory, travelling in large groups/schools, typically more then 20 miles off the coastline. Albacore occur in the Azores during April and again from September to December, in coastal zones, open water and around seamounts. At the beginning of July they travel southwest to Spain, between July and August they travel to the Bay of Biscay and in the winter they migrate to the Caribbean. Albacore feed in the Azores on small pelagic fish, especially chub mackerel, blue jack mackerel, boar fish and cephalopods (squid and octopus). Albacore can live between 9 – 13 years. Conservation status: Near threatened.

In other languages (yellowfin | bluefin | bigeye | alabcore):
Portuguese: Atum-de-galha-à-ré | Atum-rabilho | Patudo |  Voador
Spanish: Atún de aleta amarilla | Atún azul | Atún patudo | Atún blanco
French:  Thon jaune | Thon rouge du Nord | Thon obèse germon/thon blanc
Italian: Tonno pinna gialla | Tonno rosso | Tonno obeso | Alalunga/alalonga
German: Gelbflossen-Thun Rote Thun | Großaugen-Thun | Weiße Thun/Langflossenthun
Dutch:  Geelvintonijn | Blauwvintonijn | Grootoogtonijn | Witte tonijn
Swedish: Gulfenad tonfisk | Röd tonfisk eller blåfenad tonfisk Storögd tonfisk | Långfenad tonfisk
Norwegian:  Gulfinnetun Makrellstørje Storøyd tunfisk | Albakor
Danish:  - | - | - | -
Finnish:  Keltaevätonnikala Tonnikala Isosilmätonnikala | Valkotonnikala
Polish: Tuńczyk żółtopłetwy Tuńczyk pospolity |  -  | Tuńczyk biały
Russian:  Желтопёрый тунец Обыкновенный тунец Большеглазый тунец | Длиннопёрый тунец

Yellowfin tuna

Yellowfin tuna

Yellowfin tuna

Bluefin tuna

Bluefin tuna

Bigeye tuna

Tuna sp. and a dolphin

Skipjack tuna fact sheet

Katsuwonus pelamis | Skipjack tuna

The skipjack tuna is a migratory species distributed in waters between 14.7° C and 30° C, but absent in the Black Sea and the Eastern Mediterranean. Skipjack tunas are epipelagic and rarely found at depths exceeding 260 m and 15° C. The general time for spawning is between the beginning of autumn and spring, though it may be year-round near the regions around the Equator. Fertility changes with body size, with the number of eggs per season in females ranging from 80, 000 to 2,000,000. The skipjack tuna is the most caught species in tuna the fishing industry in the world, including in the Azores. They normally appear in Azorean waters between July and October, but can stay until December. 


Maximum: 1.11 m
Azores about 50 cm
Breeding size: 40 - 55 cm (age about 1.5 years)

Average 23.5 - 32.5 kg
Maximum: 34.5 kg
Azores: about 4 kg

Diet: small fish, crustaceans, cephalopods and other molluscs

Longevity: 6 - 12 years

Conservation status: Least concern. Currently there is no evidence that the population in the Atlantic is being affected negatively by the fisheries. 

In other languages
Portuguese: Bonito
Spanish: Listado/rayado/bonito
French: Bonite à ventre rayé
Italian: Tonnetto striato
German: Echte Bonito
Dutch: Echte bonito
Swedish: Bonit
Norwegian: Bukstripet bonitt
Danish: - 
Finnish: Boniitti
Polish: Bonito/ryba
RussianПолосатый тунец
Related Posts Plugin for WordPress, Blogger...