You are here: Home / Archives for Marine Science / Vertebrates / Fish

What are skates and how are they different from rays?

April 17, 2012 by Leave a Comment

Recently, a subscriber wanted to learn more about skates. Great question since many of us think of ‘roller’ when we think ‘skate’. Skates are a species that often get overshadowed by rays, especially considering rays tend to be boldly colored while skates tend to be rather dreary and drab in coloration. Rays are also found closer to the coast and skates prefer deep water so we may be more familiar with running into (or focused on learning to avoid) rays. However, there are exceptions to those generalizations within the 100 species of skates and 240 species of rays found worldwide.

They’re both flat diamond-shaped fish with their mouths on the underside of their body. Both of their body types can be described as dorsoventral. Skates and rays are cartilaginous fish, like sharks and chimaera, which all make up the class Chondrichthyes (Con-drick-thees). Cartilage is the material that makes up our nose and ears and is more flexible than bone. Skates and rays  have modified fins, resembling wings, and often look as though they are flying through the ocean.

Here are six general guidelines for differentiating a skates and rays.

  • The pelvic fin of skates is divided into two lobes, while the pelvic fin of rays is a single lobe.
  • The tail on skates lacks a stinging spine. Rays have a distinct, saw-edged spine found midway along their body length. (When swimming in the habitat of stingrays it is important to remember to do the ‘stingray shuffle‘.)
  • Many species of skates have bucklers (thorn-like scales along the mid-line of their back and tail. Rays typically have no bucklers.
  • The tail of skates is rather thick and compact, while rays typically have a slender and long tail.
  • Male skates have enlarged scales near their eyes and wingtips, known as ‘malar’ and ‘alar’ spines.  Male rays do not have these scales.
  • Skates live in cold waters, while rays prefer warm seas and rivers.

For more information about skates and rays, check out the ReefQuest Centre for Shark Research.

Photo (c) www.animals.howstuffworks.com

Filed Under: Fish, Skates and Rays Tagged With: , , ,

An important call for more forage fish to remain in the sea

April 16, 2012 by Leave a Comment

A report titled “Little Fish Big Impact”, written by the Lenfest Forage Fish Task Force, came out earlier this month recommending that the amount of forage fish (e.g., menhaden, herring, shad) that we take from the ocean should be cut in half. However, since forage fish have an annual value world-wide of $5.6 billion dollars and are almost 40% of the world’s commercial fish catch these suggestions might be a tough sell to get passed through many decisions makers. But, here is why it is important we do.

You may not typically think of forage fish, also know as ‘bait fish’, as being a high commodity for fishermen or as playing an imperative role in the ocean – but, they do indeed! It’s surprising how much these little fish play a role in our daily lives.

Within the marine food web we begin with the tiny microscopic phytoplankton (plants that get their energy from the sun). Phytoplankton are  then in turn grazed upon by tiny copepods and  they are then fed upon these forage fish and crustaceans that are fed on by larger fish (e.g., striped bass, bluefish) that are then fed upon by the top predators (e.g., tunas, swordfish) that then feed us. Easy, right? Well, Dr. Daniel Pauly pointed out that within fisheries what is happening today is an imbalance of ‘Fishing Down the Marine Food Web’.

Time increases toward the right along the blue arrow. Scale on the right gives the trophic level in the food web. (Pauly, 2003)

This is the concept that when top predators are removed smaller fish become more of a target. Which would mean that the average trophic level of the food web would shift (Trophic being the level an organism occupies within a food chain). Specifically, forage fish are the primary source of protein for penguins, marine mammals, cod, salmon, tuna, and even puffins. We use these species for the production of fish oil supplements, food for livestock, and food provided to the fish we’re farming via aquaculture.

The Lenfest Report provides information and recommendations to fisheries managers in a three-tiered approach that the Task Force says was lacking prior, which is why we’ve currently been able to harvest the amount of forage fish at such high levels. The three-tiered approach involves understanding the 1) dynamics of the fishery, 2)  knowledge of the status of the trends of the fishery’s predators, as well as 3) recommended management actions.

“Traditionally we have been managing fisheries for forage species in a manner that cannot sustain the food webs, or some of the industries, they support. As three-fourths of marine ecosystems in our study have predators highly dependent on forage fish, it is economically and biologically imperative that we develop smarter management for these small but significant species,” stated Dr. Ellen K. Pikitch of the Institute for Ocean Conservation Science at Stony Brook University (they led the Lenfest Forage Fish Task Force).

Most recently, managers in the Mid-Atlantic have noticed the increasing importance of forage fish and voted to reduce the annual harvest of menhaden from 183,000 metric tons to 174,000. Read more here on the report and what other measures are being done to keep menhaden levels more sustainable.

It will be interesting to see how this report impacts forage fisheries in the future. I certainly hope it does.

Check out this video from the Task Force to learn more on the importance of forage fish.

Lastly, here is a quick overview of what it means to be a sustainable fishery:

  • If we are referring to a sustainable wild fishery (one that is not farmed) it could be the measure of the abundance and resilience to fishing pressure, how well-managed the fishery is based on current research, and/or that the fishery is harvested in ways that do not harm the environment or have negative interactions with protected species as bycatch.
  • With farmed species a sustainable it is typically a measure of minimizing marine resources, preventing escapes or diseases to wild stocks, as well as ensuring that the fishery is not associated with high pollution or other ways of negatively harming the habitat.
  • For a good resource to discover what fishery is sustainable in your region,  please check out the Monterey Bay Seafood Watch.
Filed Under: Biodiversity, Birds, Bony Fishes, Fish Tagged With: , , , , , , , , , , ,

The Bluefish by Isaac McLellan

April 2, 2012 by Leave a Comment
Bluefish

Bluefish (Photo credit: Wikipedia)

I hope you enjoy this poem about a very popular Atlantic coast recreational species, the bluefish. I have some fond childhood memories aboard my grandparents boat, Irish Eyes, learning many life lessons while seeking out bluefish.

Issac McLellan (1806 – 1899) was a New England author and poet. Coincidentally, he was born in Portland, Maine which is where we’re headed today! Enjoy.

The Bluefish by Isaac McLellan

(Pomatomus Saltatrix.)

It is a brave, a royal sport,
Trolling for bluefish o’er the seas;
Fair skies and soaring gulls above,
A steady blowing breeze;
A shapely yacht whose foaming prow
The billowy plain divides,
That like a gallant courser speeds
Far, free o’er ocean tides.

First from West India seas they came,
Haunting the Cuban coast,
Cruel as Spanish buccaneers,
A fierce, rapacious host.
But now by Northern seaboard shores
Their murderous way they take,
From Mexico Gulf to Labrador,
Wherever billows break.
The weaker tenants of the main
Flee from their rage in vain,
The vast menhaden multitudes
They massacre o’er the flood;
With lashing tail, with snapping teeth
They stain the tides with blood.

Rakish are they, like pirate craft,
All matchless to assail,
With graceful, shapely, rounded sides
And the sharp, forked tail;
And when the angler’s hook is fixed
They fight, they struggling bleed,
Now leaping high, now plunging deep,
Darting with lightning speed.

And yet these sea marauders,
These tyrants of the main,
By fiercer, mightier ruffians
Are hunted, conquered, slain;
The tumbling porpoise hunts them,
Dorado fierce pursues,
And when the shark assaileth,
Blood-stains the waves suffuse.

Filed Under: Bony Fishes, Fish, Random Fun! Tagged With: ,

Can you name the state fish of Hawai’i?

April 1, 2012 by 2 Comments

It’s “Humuhumunukunukuāpua’a” in case you missed it when the bartender mentioned it in Forgetting Sarah Marshall. As a bonus, I’ll also give you a rundown of all the other states with a state saltwater/game fish. Some you may already know, but  some might surprise you! I never would have thought that so many states have striped bass designated as a state fish or state saltwater fish. After all, there are over14,000 species of saltwater fish out there.

(If I missed one please feel free to let me know and I’ll add it to the list. All you have to do is leave a comment of email info@beachchairscientist.com.)

Alabama:
Fighting tarpon (Megalops atlanticus) – These fish can absorb oxygen and live in waters with almost no oxygen.

Alaska:
King salmon  (Oncorhynchus tshawytscha) – These fish regularly exceed 45 lbs and the largest on record was a 126 lb caught in 1949.


California:
Garibaldi (Hypsypops rubicundus) – These fish are very territorial and call kelp forests home of choice.


Connecticut:
American shad (Alosa sapidissima) – These fish only have one dorsal fin and one anal fin.


Delaware:
Weakfish (Cynoscion regalis) – These fish are not weak at all but quite strong fighters. The name refers to the easily torn part membrane in its mouth.  A fond memory of my childhood involves my grandfather always giving my folks some weakfish he caught on his boat, Irish Eyes.


Florida:
Atlantic sailfish  (Istiophorus albicans) – These fish are the fastest fish in the sea and have been observed at speeds above 65 miles per hour.

Hawai’i:
Humuhumunukunukuāpua’a (Rhinecanthus rectangulus) – This fish has blue teeth.

Maryland:
Striped bass (Morone saxatilis) – These fish are also commonly known as rockfish.

Massachusetts:
Cod (Gadus morhua) – These fish will change colors depending on where it spends its days. If it prefers the sea floor it will appear gray and if it prefers algal areas it will appear greenish.

North Carolina:
Red drum (Sciaenops ocellatus) – These fish got their name from their coloring and from the drumming sound produced by their  their swim bladder.

New Hampshire:
Striped bass (Morone saxatilis) – These fish prefer coastlines and are most active in the spring and fall. Sport fishermen love to catch them during the striper runs.

New York:
Striped bass (Morone saxatilis) – These fish are the most popular sportfish on the Atlantic coast. 

Rhode Island:
Striped bass (Morone saxatilis) – These fish prefer to eat before dawn and at dusk. 

South Carolina:
Striped bass (Morone saxatilis) – These fish do not have eyelids so when the sun is out they prefer to retreat to deeper waters.

Filed Under: Biodiversity, Bony Fishes, Fish, Places, Random Fun! Tagged With: , , , , , , , , ,

April is National Frog Month

April 1, 2012 by 2 Comments

Yes, that is correct – April is National Frog Month. However, this is not a post about the amphibian, but is all about the frogfish! Contrary to popular belief, it’s easy being green if you’re a frogfish. First of all, you can change colors from green to black, or red, or orange, or yellow, or brown, or white, or purple, or even blue! These colors help the frogfish mimic corals, sponges, algaes, or even rocks. Often a trusting fish become prey all too easily as they go to hide in the ‘coral’ or ‘rock’ only to then get eaten by the frogfish that has transformed . Frogfish gobble up their prey in 6 milliseconds. Frogfish actually have the fastest mouth in the sea. Their mouth is able to expand 12 times its size and they can easily eat prey 25 percent longer. They’re opportunistic and eat whenever possible. They tend to feast on smaller fish, crustaceans, or even other frogfish!

Another amazing mechanism of the frogfish is an antenna that dangles from their head. They’ll mimic the actions of a smaller animal (e.g., a worm or shrimp) with this antenna so that their own prey will swim right up to them. Don’t worry though, the lure will regenerate if eaten.

Frogfish do not have a swim bladder, but do have modified pectoral fins enabling them to ‘walk’ along the seafloor. See the video below to see this in action.

Frogfish live in the tropical and subtropical areas in the Atlantic, Indian, and Pacific Oceans.

It is the original footage from these hairy frog fish walking on the sand was made by Daan van Wijk in Indonesia. These scenes are from the movie Impressionesia”.

Filed Under: Algae (Seaweeds), Animal Homes, Bony Fishes, Crustaceans, Fish Tagged With: , , , ,

‘Wicked Tuna’ is food for thought

March 31, 2012 by 2 Comments

Tomorrow the National Geographic Channel (of which approximately over 50% is owned by NewsCorp, a Murdoch Company) is debuting the television show Wicked Tuna. The show is intriguing because the species itself is remarkable.

Atlantic bluefin tuna (Thunnus thynnus) can swim up to 40 miles per hour and can dive up to 3,000 feet. Their body is so remarkably streamlined for efficiently swimming through the ocean that Pentagon-funded scientists have studied the species as a model for Navy torpedoes. They’re also known to travel far and wide (actually, across entire oceans over their lifetime). This causes some challenges when coming together to manage the species.

The dilemma I have in deciding to watch the show is that NatGeo may be glorifying the bluefin tuna as a species of consumption so that people start ordering it more. But, folks need to understand the repercussions and ask one more question, “Is this bluefin tuna caught in the U.S.?”

As I mentioned, there are some challenges with managing a species that spans globe. Bluefin tuna are an internationally managed species, guided by the intergovernmental body the International Commission on Conservation of Atlantic Tunas (ICCAT). Within management plans of the ICCAT, it is irrefutable that the U.S. bluefin fishery is the most sustainably managed in the world. The bluefin tuna caught in Maine, New Hampshire, and Massachusetts is predominantly hand gear (rod and reel or harpoon). This fishery is well regulated and responsible. There is also bluefin tuna caught as bycatch from the longline fisheries targeting other types of tuna. To reduce bycatch, fisheries are now required to use circle hook and weak hooks to reduce the bluefin tuna bycatch, as well as other nontarget species (e.g., sea turtles). The species is slow to mature and catching young bluefin tuna reduces the chance they’ll have the opportunity to reproduce. That is why it is so negligent to eat the bluefin tuna from the poorly regulated European fishery. Many of the bluefin caught there are with purse seines or longlines. In fact, since industrial fishing began in the Mediterranean it is estimated that over 80 percent of bluefin stocks have been fished out.

It’s no help that there is extreme demand for this type of fishing pressure as sushi chefs will pay gobs for the fish. The ‘Wicked Tuna” fishermen can get up to $20,000 for each fish. In January 2012, a Tokyo restaurant paid $736,000 for a bluefin tuna at auction (there’s the ‘first fish phenomenon’ which can bring a lot of publicity to a restaurant for paying a high amount for the first fish). Click on https://www.altitude-sports.com/collections/footwear-men-hiking-boots to find the best quality camping equipment for you.

The Monterey Bay Seafood Guide lists bluefin tuna as a species to avoid. The Center for Biological Diversity encourages the public to boycott any restaurants serving bluefin tuna. Greenpeace has even stated that, “The world needs to see a ban on bluefin tuna fishing until stocks recover”. National Geographic claims this show’s scope includes a “solid conservation message about what’s been going on with the bluefin”. So, if you must ask for ‘Wicked Tuna’, make sure it’s at least from the U.S. Certainly, food for thought.

Filed Under: Biodiversity, Bony Fishes, Fish, Ocean Tagged With: , , , , , ,

Cirque Du Baille (or Circus of the Sea)

February 23, 2012 by 2 Comments

Now that my little one is getting to the age where she’s off on fun excursions with daycare (today she went to the National Zoo!), I started having nightmares she might ask her father and I to take her to the circus.  I haven’t been to the circus since I was 6 and am not even certain if they still have them or that I want to take her. I do love the idea of taking her to Cirque Du Soleil to enjoy the music and dancing, though.

Then I started to daydream …  “What if I could take her to a circus of the sea“? So, here is my representation of “Cirque Du Baille” featuring the spinner dolphin as the amazing acrobat, the clownfish as everyone’s favorite (or creepy) jokster, the dumbo octopus as the ideal replacement for the elephant, and once the lionfish figures out a way to get those tentacles through hoops he’ll take down the big top.

Filed Under: Animal Homes, Cephalopods, Coral Reef Ecosystems, Fish, Marine Mammals

What is shark finning?

February 1, 2012 by 2 Comments

There has been a lot in the news recently about shark finning. It’s the inhumane practice of capturing a shark, slicing its fins off (shark fin soup is an expensive delicacy popular at Chinese weddings and Chinese New Year celebrations), and tossing the rest of the animal overboard to bleed out a die.

As noted on the Save Our Seas Foundation website, “Compared to other commercial fisheries, the shark-fin industry is opaque, secretive, and often operates in a legal grey area, exploiting loopholes in anti-finning laws and keeping few records. In addition to this, reporting can be unreliable and misleading, as member countries of the UN Food and Agriculture Organisation (FAO) report shark catches with varying degrees of detail and accuracy”. There is some forward momentum. A ban has been put in place in California, Hawaii, Oregon, and Washington to end the practice. California will also implement a ban on the importation of fins starting January 1, 2013. Although, as the LA Times writes, it is still an uphill battle in China.

Wildaid, in conjunction with artist Kiki Karpus, created this powerful “What is shark finning?” infographic as a way to understand more on the harmful effects the practice has on the entire ocean ecosystem.

Filed Under: Sharks Tagged With: , ,

How is it I can find some species of fish in fresh and saltwater?

January 30, 2012 by 3 Comments
The striped bass is the main piscivore of the LSZ

Striped bass

Some species of fish can regulate their salt tolerance easier than others. For instance, many of the species that call the estuary a nursery or breeding ground can adapt to a wide range of salinity (less than 30 ppt). These animals (or plants) are known as euryhaline. Other animals that cannot tolerate a wide range of salinity are known as stenohaline. Some euryhaline species include striped bass, mummuichug, puffer, shad, herring, and sturgeon.

Filed Under: Fish Tagged With: , ,

Happy Chinese New Year … Year of the (Sea) Dragon!

January 22, 2012 by 1 Comment

Happy Chinese New Year … Year of the (Sea) Dragon!

January 23 will bring a very significant celebration for those that live by the sea … it is the year of the water dragon which only occurs every six decades! To commemorate such an occasion, BCS will highlight two very remarkable and elaborate dragons found off the coast of south and east Australia. The leafy seadragon (Phycodurus eques) and the weedy seadragon (Phyllopteryx taeniolatus) are related to the more familiar seahorse and pipefish.

Leafy Seadragon

Although they may share the similar feature of a long snout with the seahorse and pipefish, the seadragon’s appendages coming from their solid, armor-like skin are what really set them apart. The leafy seadragon, often yellowish-green, is much more ornate than the reddish colored weedy seadragon. Although, the weedy seadragon does have some striking bright blue bands along its upper body. Unlike seahorses,  seadragons do not use their tails to grasp onto the seaweeds or algae that they call home. In fact, the seadragons prefer to drift although they can use their transparent dorsal and pectoral fins to help navigate.

Weedy Seadragon

Similar to seahorses, male seadragons do the child bearing. The males have a brood patch under their tails (unlike the seahorse that have a pouch on their belly). The female will lay approximately 250 eggs on the patch at the time of fertilization and the eggs will hatch approximately 6 weeks later. The tiny juvenile seadragons look exactly like their parents but are immediately independent from them. This is their most vulnerable time of life when they may be eaten by various anemones, crabs, or hydroids. But if they avoid these predators and eat plenty of zooplankton the seadragon will grow to be either 14 inches (leafy) or 18 inches (weedy). The adults usually feast on sea lice or mysid shrimp. Of course, that is also if they manage to evade people collecting them for black market aquariums and staying away from areas where there is pollution and habitat loss.

Other interesting facts about seadragons are that their eyes move independently and they have no teeth or stomach!

Resources:

  • http://australian-animals.net/dragon.htm
  • http://animals.nationalgeographic.com/animals/fish/sea-dragon/
  • http://www.montereybayaquarium.org/efc/efc_splash/splash_animals_seadragon.aspx
Filed Under: Algae (Seaweeds), Egg Cases, Fish Tagged With: , , , , ,