Fishes Archives - vic high

Thresher Shark

Thresher shark

Author: Keira Lane

Common name: Common thresher shark, Atlantic thresher shark

Scientific name: Alopias vulpinus

Size range: The common thresher shark is the largest species of thresher shark in the world and in Canadian waters they are generally between 3.3 to 5.5 meters (10.8 to 18 feet) in length, though some can be up to 6.1 meters (20ft) in length.

Identifying features: The common thresher sharks have a short dorsal fin and an enormous upper caudal fin that’s 50 percent of the total length of the shark. They have a short snout with large eyes placed forward on the head. They also have relatively small teeth in their jaws for a shark. There are 3 types of thresher sharks, common thresher, pelagic thresher, and the bigeye thresher. Depending on the type of thresher shark they can be gray, blue, brown, or purplish in colour. The common thresher shark is a dark bluish-grey on top with a metallic reflection on their side. The dorsal and pectoral fin has an extended dark coloration.

Habitat: The common thresher shark can be found in all of the warm and temperate oceans of the world. On the Pacific coast it is found from British Columbia, Canada to Oregon in the US. They mostly swim at the surface of the continental shelf but they can also occur at depths of 1,200 feet or more. Younger common thresher sharks can be found in shallower waters and like jumping out of the water, a behavior called breaching. The adults migrate seasonally with the males traveling farther northwards and reaching the coast of British Columbia in the late summer. The common thresher sharks must keep swimming so that water flowing over their gills will oxygenate their blood.

Food/Prey: The common thresher shark is a predator of fish. They are solitary creatures and usually never hunt in groups. They mainly feed on schooling fish, cephalopods, squids, crustaceans and sometimes seabirds. They splash the water to frighten them forcing fish to form tighter schools. Sometimes they use their long tails to stun their prey. The marine animals that are most likely to prey on the thresher sharks are Killer whales and larger sharks. The thresher shark isn’t dangerous to humans but can cause damage to fishing gear. .

Life Cycle: Thresher sharks can live up to at least 19 years old and mature in 3 to 8 years. The females are ovoviviparous and give live birth to 2 to 6 pups that are around 1.5 metes (5 feet) in length. Due to the long time it takes for maturity the thresher shark is at risk of being overfished.

References:

De Maddalena, A., Preti, A., & Polansky, T. (2007). Sharks of the Pacific Northwest: Including Oregon, Washington, British Columbia and Alaska. Harbour Pub.

Hart, J. L. (1973). Pacific fishes of Canada. Fisheries Research Board of Canada.

(2019, January 30). Thresher shark. Retrieved January 19, 2024, from https://www.dfo-mpo.gc.ca/species-especes/profiles-profils/threshershark-renardmarin-atl-eng.html#

May 14, 2024/0 Comments/by David Young

Fishes

Bluntnose Sixgill Shark

Bluntnose sixgill shark

Scientific Name: Hexanchus griseus (Bonnaterre, 1788)

Authors: Christian and Elijah’s

Photo: Thank you to Andy Murch for the use of his photo.

Identifying features Unlike the typical 5 gill slits, like the name suggests, this fish has 6 long pairs of gill slits. The gill slits get shorter the farther away they are from the head. Their back is shaped in a somewhat hunched manner, with their dorsal fin far back over the posterior part of the pelvic fins. Pectoral fins are largely wide compared to their moderate length. Their unique fin size continues to their caudal fins, as the upper lobe is very long compared to the short lower lobe. The short lower caudal lobe is comparable in size to their dorsal fin. Their uniqueness continues with their body shape, as they have a wide and rounded head with relatively large fluorescent green eyes compared to their massive up to 15 ft long dark brown, grey, or black body. (De Maddalena et al., 2007, 83) (Bester, 2023)

Habitat They can be found in deep habitats all around the world, yet they can be quite commonly found in local Pacific Northwest waters, such as Hornby Island. They are mainly found on continental shelves, insular shelves, and slopes at depths ranging from 0 to 2,500m (8,200 ft) below sea level. Juveniles normally inhabit more shallow waters compared to adults. (De Maddalena et al., 2007, 85)

Florida Museum, Discover Fishes, Hexanchus griseus World Distribution map of the bluntnose sixgill shark. (Bester, 2023)

Local Diving Spots Hornby Island and Flora Islet in the Strait of Georgia, British Columbia, is a known diving hotspot for finding these sharks in the region. The best time to see them here is during the warmer summer months, especially during the afternoons of the hottest times of the year, mid-June and mid-July. Recommended depth for sitings is 18-30 M (60-100 ft) below sea level. They have also been encountered off of Saanich Inlet and Barkley Sound while diving. (De Maddalena et al., 2007, 85)

Food (Prey) They seem to eat a mix of fishes, such as other local sharks, cephalopods, sea urchins, or dead carcasses. Pretty much anything that they can fit in their mouth, as they’ll either hunt via ambush or scavenge. They have only been observed to hunt solitarily, yet at extreme depths, they can be seen eating large whale carcasses, being a very prized meal. (Bester, 2023) (De Maddalena et al., 2007, 85)

Predators Certain sea mammals may present to be dangerous to these fishes in shallow waters, such as Steller’s sea lions, or orca.. Great white sharks have also represented predatory patterns upon these sharks, a dangerous predator to these slow moving fish.

Life Cycle These fish are born live out of the womb in litters of 22 all the way up to 108. As of 2023, it is not fully confirmed how long they live for, but it is likely that they live up to 80 years, and reach maturity around 11-14 for males and 18 – 35 for females.

Fun Facts:

largest member of the Cow sharks
They have been known to attack submarines (BBC News, 2017)
They are suction feeders.
Not hostile towards humans, represent little threat. (Bester, 2023)
Their earliest ancestors date back to over 200 million years.
They are slow moving yet powerful ambushers. (Bester, 2023)
Unlike other sharks, they are not born out of an egg. (Bester, 2023)

References

BBC News. (2017, November 9). https://www.youtube.com/watch?v=ZqBfyocxqr4&t=110s. YouTube. Retrieved January 25, 2024, from https://www.youtube.com/watch?time_continue=110&v=ZqBfyocxqr4&embeds_referring_euri=https%3A%2F%2Ffactanimal.com%2F&source_ve_path=MjM4NTE&feature=emb_title

Bester, C. (2023, December 28). Hexanchus griseus – Discover Fishes. Florida Museum. Retrieved January 25, 2024, from http://floridamuseum.ufl.edu/discover-fish/species-profiles/hexanchus-griseus/

De Maddalena, A., Preti, A., & Polansky, T. (2007). Sharks of the Pacific Northwest: Including Oregon, Washington, British Columbia and Alaska. Harbour Pub.

Hart, J. L. (1973). Pacific fishes of Canada. Fisheries Research Board of Canada.

January 26, 2024/0 Comments/by adam.james

Fishes

Three-spined Stickleback

Three-Spined Stickleback

Author: Anil Mishra

Photos: Anil Mishra and D. Young

Common Name: Three-Spined Stickleback

Scientific Name: Gasterosteus aculeatus

Size range: 5-10 cm

Habitat: The Three-Spined Stickleback can be commonly found in British Columbia but they have also been found in the Bering Sea, Northern California, and parts of East Asia. They can tolerate many water conditions and may live in fresh water lakes, ponds and ditches, brackish water, as well as in the ocean. They are often found in schools in shallow water along docks in the Pacific Northwest.

Food (Prey): The main diet of the Three-Spined Stickleback in fresh water are water fleas mayfly larvae, and sometimes smaller fish. In the ocean they eat a variety of small plankton and invertebrates such as copepods.

Predators: Bigger fish will try to catch the Three-Spined Sticklebacks but the Stickleback’s armour can protect them. The Three-Spined Stickleback is also pretty aggressive and will fight off predators which can result in some bigger fish avoiding them.

Identifying Features: The Three-Spined Stickleback has 3 pointed spines at the top, bony plates on the side that act as armour, and a spine in the pelvic fin. It is usually coloured silver, green, blue or black but in freshwater they are usually brown. During breeding the males’ throat region becomes bright red and the eyes a striking blue.

Illustration by D. Young

Behaviour: The Three-Spined Stickleback are actually pretty social and will sometimes join groups of fish that look similar to them. They are often studied for their behaviour during courtship, mating and when protecting their territory.

References

Gotshall, D. (2001). Pacific Coast inshore fishes. Sea Challengers, Incorporated.

Lamb, A., & Edgell, P. (2010). Coastal Fishes of the Pacific Northwest Revised and Expanded Second Edition. Harbour Pub.

Lamb, A., Lamb, A., & Edgell, P. (1986). Coastal Fishes of the Pacific Northwest. Harbour Publishing.

Threespine stickleback. (n.d.). Wisconsin Sea Grant. Retrieved January 24, 2024, from https://www.seagrant.wisc.edu/our-work/focus-areas/ais/invasive-species/invasive-species-fact-sheets/fish/threespine-stickleback/

Wood, S. (2020). ADW: Gasterosteus aculeatus: INFORMATION. Animal Diversity Web. Retrieved January 15, 2024, from https://animaldiversity.org/accounts/Gasterosteus_aculeatus/

January 25, 2024/0 Comments/by adam.james

Fishes

Penpoint Gunnel

Penpoint Gunnel

Author: Oscar Schuckel-Bailey

Photos by Oscar Schuckel-Bailey and D. Young

Common name: Penpoint Gunnel

Scientific name: Apodichthys flavidus

Size range: The Penpoint Gunnel can grow up to 46 centimetres (18 inches)

Identifying features: Penpoint Gunnels can be a range of colours, from wine red to emerald green to golden brown. They are elongated fish with long and low dorsal fins. They lack pelvic fins and can be differentiated from their close relative, the Rockweed Gunnel (Xerepes Fucorum) by having slightly larger pectoral fins and a more distinct eye bar (this stripe is usually vertical, although in some cases it occasionally can be horizontal).

Habitat: Penpoint Gunnels are often found in either the subtidal or intertidal zones. Their colouring largely depends upon their food and as adults they hide in matching seaweed or seagrass; green with sea lettuce or eelgrass, red with red seaweeds and brown with similar brown/golden kelp. They also often hide under rocks during high tide.

Food: Penpoint Gunnels prey on small crustaceans, polychaetes, mollusks as well as fish eggs.

Predators: As they are small fish, Penpoint Gunnels have a lot of predators including sea birds, River Otters and larger fishes such as adult salmon. Their primary method of defense would be their camouflage and their ability to fit in small cracks and crannies.

References:

De Forest, L. G., & Busby, M. S. (1970, January 1). Development of larval and early juvenile penpoint Gunnel (Apodichthys Flavidus) (family: Pholidae). Welcome to AquaDocs. Retrieved January 26, 2023, from https://aquadocs.org/handle/1834/25597

Gunnel and prickleback care purpose: Policy: Responsibility: Procedure. (n.d.). Retrieved January 27, 2023, from http://www.bamfieldmsc.com/wp-content/uploads/2016/08/AC_GUNNEL_PRICKLEBACK_SOP_V01.pdf

Lamb, A. & Edgell, P. (1986). Coastal Fishes of the Pacific Northwest. Harbour Publishing.

Lamb, A., Penpoint Gunnel • Apodichthys Flavidus. Biodiversity of the Central Coast. (n.d.). Retrieved January 26, 2023, from https://www.centralcoastbiodiversity.org/penpoint-gunnel-bull-apodichthys-flavidus.html

September 15, 2023/0 Comments/by adam.james

Fishes

Greenland Shark

Greenland Shark

Author and Illustrator: Ella Williams

Photos: Thank you to Andy Murch for the use of his Photos

Common name: Greenland Shark, Gurry Shark, Grey Shark

Scientific name: Somniosus microcephalus

Size: generally 8 to 14 feet in length (up to 24 feet)

Identifying Features One of the largest living sharks, the Greenland Shark is a pale warm gray. Although they are commonly 8-14 feet long, Greenland sharks as large as 24 feet have been recorded. It is part of the Sleeper Shark family Somniosidae. The Greenland shark is heavy-set, with rounded features and disproportionately small fins for its size. It has five to six small gills.

Habitat The Greenland shark lives in the northern Atlantic and Arctic Ocean, although newer studies show it may go as far as the Caribbean at great depths. Generally, the Greenland shark swims in very deep waters, but occasionally returns to the surface to feed.

Food (Prey) The Greenland shark is a generalist feeder that mostly feed on fish, however, it has been known to eat a variety of creatures, including polar bears, reindeer, horses and other large land mammals.

Predators The Greenland shark has no natural predators other than humans. It is eaten as a delicacy in Iceland.

Life Cycle Greenland sharks give live birth and can have up to ten pups. Interestingly, greenland shark pups are not connected to a placenta, and rather survive off of yolk sacs. They have an incredibly long gestation period of 8-18 years, and are thought to be able to give birth to 200 to 700 pups during their lifetime. Greenland sharks mate via internal fertilization.

Fun Facts Most Greenland sharks are blind! They are prone to parasitic copepods called Ommatokoita attaching themselves to their corneas, causing severe vision loss. It is theorized that these parasites could have a potentially mutualistic relationship with the shark, as they could provide bioluminescence and attract prey. This has not been proven. Another fun fact is that Greenland Sharks are estimated to live up to 250 years and possibly over 500 years making them the longest living vertebrate on the planet!

References

How long do Greenland sharks live? (n.d.). NOAA’s National Ocean Service. Retrieved August 28, 2023, from https://oceanservice.noaa.gov/facts/greenland-shark.html

Greenland Shark. (n.d.). Oceana. https://oceana.org/marine-life/greenland-shark/

Government of Canada, F. and O. C. (2016, December 19). Greenland shark. Www.dfo-Mpo.gc.ca. https://www.dfo-mpo.gc.ca/species-especes/profiles-profils/greenlandshark-laimargueatlantique-eng.html

‌Greenland shark | Size, Age, & Facts. (n.d.). Encyclopedia Britannica. https://www.britannica.com/animal/Greenland-shark

Greenland shark. (2021, November 7). Wikipedia. https://en.m.wikipedia.org/wiki/Greenland_shark

August 28, 2023/0 Comments/by adam.james

Fishes

Sunfish – Mola mola

The Ocean Sunfish

Scientific name: Mola mola

Authors: Ethan and Duncan

Photo by Per-Ola Norman

Features: Sunfish are very interesting creatures. They are so weird that they don’t even look real, they look like something from another planet. But sunfish are very real and very fascinating. The average adult Sunfish grows up to about 1.8 meters. That’s about the size of a full grown person. They are round, flat and oval shaped with a very large dorsal fin at the top and an anal fin at the bottom. The caudal fin of some Sunfish stretches to the height of their bodies. Thier mouth is constantly open because of the way their teeth are structured. They have a beak like teeth that can chew up things like jellyfish. Near the middle of their body are pectoral fins, they use these fins to swim and change direction.

Habitat: Sunfish are generally an open-water fish that like to live anywhere that it is warm. Despite this sometimes they will be found far off the coast of the Pacific Northwest in the clear warm water currents that flow up in the summer. In general they mostly live in the warm tropical waters of Australia, New Zealand, Chile, and South Africa. They live in depths of around 100m to 200m and spend their time alone or with one other Sunfish.

Food: The Mola mola’s diet used to be considered mostly made up of jellyfish but stomach analysis have shown that is has a very diverse diet depending upon the food it comes across. The diet consists of mostly small fish and jellyfish, but also crustaceans and even eelgrass. Mola mola are very slow and have trouble keeping up with their prey s0 to combat this they use their mouths to inhale water creating a vacuum and sucking up their prey into their mouths.

Predators: The ocean sunfish’s main predators are creatures like sharks and sea lions. They don’t have a lot of self defense, their main source is having extremely rough leathery skin comparable to a rhinoceros. Swimming away isn’t an option either, their sheer mass and size and their lack of a “propelling” ability make them very slow. They can swim up to speeds of 3.2 kilometers per hour, while a sea lion that is hunting them can swim up to 40 kilometers per hour. Other than that they don’t really have anything to defend themselves, they can also fling themselves out of the water to defend themselves as a last resort but other than that they are pretty defenseless.

Life cycle: The female Sunfish will lay about 300 million eggs. The eggs all hatch together and swim in schools. They grow rapidly, losing a tail and growing spines. At 15mm they are in their fry stage, the fry has spikes all around their body similar to a pufferfish. By 37mm they lose their spikes and begin to look more like an adult sunfish. Upon maturity the Sunfish will leave their group and live alone or with another sunfish.

Fun Facts:

Their skin is as rough as 36 grit sandpaper

Because of its large size Sunfish act as harbours of small organisms – they can carry tonnes of different species on them

The only reason Sunfish haven’t gone extinct yet is because the female produces millions of eggs during reproduction.

In German they call the Mola Mola Schwimmender Koph, meaning swimming head.

Sunfish are very noisy. They grunt often as a form of communication.

They can also projectile poop.

References:

Ocean sunfish. (2021, January 04). Retrieved January 06, 2021, from https://en.wikipedia.org/wiki/Ocean_sunfish

Ocean Sunfish (Mola): National Geographic. (2018, September 21). Retrieved January 06, 2021, from https://www.nationalgeographic.com/animals/fish/o/ocean-sunfish/

Hausheer, J., Miller, M., & Byington, C. (2019, March 02). Meet The Magnificently Weird Mola Mola. Retrieved January 06, 2021, from https://blog.nature.org/science/2017/11/27/meet-the-magnificently-weird-mola-mola/

Kennedy, J. (n.d.). Strange Ocean Sunfish Facts. Retrieved January 06, 2021, from https://www.thoughtco.com/facts-about-ocean-sunfish-2291599

May 24, 2021/0 Comments/by adam.james

Fishes

Lemon Shark

The Lemon Shark

Author: Misha Young

Photos: Thank you to Andy Murch for permission to use of his photo

Common Name: Lemon Shark

Scientific name: Negaprion brevirostris

Size Range: Maximum recorded length – 3.4m, average length – 2.1m

Maximun recorded weight – 184kg, average weight – 90kg

Identification: The Lemon Shark gets its name from the slight yellowish tint in its skin. It is thought that this yellow colour is used for camouflage in shallow sandy shoals where it spends lots of its time. This shark also has a second dorsal fins that can be as large as the first dorsal fin. Lemon Sharks have a special and highly specialized horizontal pupal or “Visual Streak”, that when underwater, lets them see extremely fine colour and detail. At birth they are roughly 60-65 cm and they will live for an average of 25 years.

Distribution: Lemon Sharks spend most of their lives in shallow mangroves. This is where they find most of their prey, as mangroves are common breeding grounds for lots of fish. Fun fact: Some adult lemon sharks are known to hunt in the mangroves that they were born in, and will actually eat juvenile lemon sharks 😮 . Lemon sharks are typically inhabitants of coral reefs and tropical waters, and can be found in the Atlantic Ocean along the east coast from New Jersey to southern Brazil and along the west coast of Africa. They are also found in the Pacific Ocean from southern California to Ecuador. Other common places to find Lemon Sharks are docks, lagoons, salt rivers, and they will sometimes venture into the open ocean to migrate.

Life Cycle: When pregnant, female lemon sharks can carry their embryos for up to 12 months, and will give birth in the safety of shallow mangroves to up to 17 live pups. During mating, the male will actually clamp onto the female with his jaws, and then does the deed. The pups will reach sexual maturity at around 12 years. When the baby lemon sharks are mature enough, they will start to venture out into the deeper waters of the mangroves to hunt, but they need to watch out as they might become food themselves. Adult Lemon Sharks are sometimes known to return to their birthplace to hunt, for OTHER LEMON SHARKS! Adult lemon sharks will come back to their childhood mangrove home to feed on the juvenile lemon sharks. They know the area very well, and therefore will be able to predict where the pups will hide. In addition to cannibalism, Lemon sharks will also feed on relatively large reef fish, rays, and sometimes even crustaceans.

Behaviour: Lemon sharks are very social animals, and will often prefer to live in groups. Younger Lemon sharks are often known to venture out of their mangrovial home at a younger age, to join a pod of older sharks. Biologists believe that they do this to learn about hunting, and communication. Lemon Sharks are very friendly and are a welcome sight on many a tropical dive. Only ten lemon shark attacks have been reported, none of which were fatal.

Lemon sharks are near threatened, and are a very common target for poachers, looking to cut off their fins for trade in Asia. Once the fins are cut off, the poachers will dump the body of the lemon sharks back into the water where the sharks will die from its wounds.

References:

(Photograph) 16 Sites extraordinaires. (n.d.). Retrieved January 27, 2021, from https://www.mooreabluediving.com/15-amazing-sites.html

Lemon Shark. (n.d.). Retrieved January 27, 2021, from https://oceana.org/marine-life/sharks-rays/lemon-shark

Negaprion brevirostris summary page. (n.d.). Retrieved January 27, 2021, from https://www.fishbase.in/Summary/SpeciesSummary.php?ID=897&AT=lemon%2Bshark

Lemon shark. (2021, January 12). Retrieved January 27, 2021, from https://en.wikipedia.org/wiki/Lemon_shark

March 28, 2021/0 Comments/by adam.james

Fishes

Interview With Shark Photographer Andy Murch

By Anouk Janess

Andy Murch (photo, left) is someone of hidden celebrity on Vancouver Island. He is the founder and creator of Elasmodiver: Shark and Ray Field Guide, Predators in Peril Project that works to bring awareness to our vital predators of the sea, and eco-tourism business: Big Fish Expeditions. I contacted Andy over email and was able to ask him about his journey to success.

Andy Murch was born in London, England. He grew up in Pilgrim’s Hatch – a small village in Essex. About his interests as a child he says, “I grew up watching BBC documentaries with David Attenborough.” Living in the country, he could often be found in the fields or forests, far from the coast – that came much later. His parents had a pond in their yard but that was it, so he didn’t have much of a connection with the marine environment until after he dropped out of Chelmer University in Essex, and decided to travel the world.

“My career path was a little unorthodox,” says Murch. “When I quit university, I traveled through 70 countries in seven years. My first job on the ocean was as a deckhand on an Israeli schooner on the Red Sea.” Eventually, he settled down in Canada and opened an import company. This allowed him to take time off in the winter to travel to the tropics and it was then that he learned to dive and later bought his first underwater camera. At 37, in the late 90s, he quit his company to become a dive instructor and later a submersible pilot. The ocean, taunting and inviting, called to him. “I became very passionate about the ocean, especially about sharks,” he says. “They were obviously ‘cool’ but the more I learned, the more I realized they were in trouble.”

He started Elasmodiver, a play on the scientific name elasmobranchs for sharks and rays, as “my first attempt to educate others about the plight of sharks.” A few years later he started the Predators In Peril Project (PiP). PiP provides original, unedited images used to educate others about the severity of illegal fishing of elasmobranchs. From then he built a large underwater photography portfolio with many shark and ray images from which he was able to make a modest living. He clarifies that he still had to get odd jobs now and then to supplement his income. Once he made a name for himself as a shark photographer, he started running the very busy, very successful eco-tourism business, Big Fish Expeditions, which offers diving trips to the world’s best places to see and photograph sharks, rays and whales in their natural habitat.

Mr. Murch explains to all young people considering their future career path that it was very important for him to find a career where he could live comfortably, do what he loves (working with animals) and be able to help protect the environment in some way. “Obviously, I didn’t have a traditional career plan,” he says. “The key was to identify career opportunities when they presented themselves and then not be afraid to stop what I was doing and seize those opportunities.” Andy Murch started with little more than a camera and a sense of curiosity, but now, thanks to his work and images, humans on land can gain a better understanding of sharks and rays, these misunderstood and imperiled creatures from deep within the ocean.