[seaslug44]

Very bad news guys...

Remember that huge crab bloom that we had last month in the LI Sound that spread billions of tiny crabs from Rocky Point all the way to the City bridges and everywhere in between? Well I kept a dozen of those critters in my saltwater tank to see what they would grow up to be.

The bad news is that they are Asian Shore Crabs (Hemigrapsus Sanguineus), also known as Japanese Shore Crabs. I learned about this invasive species last month when we were talking about keeping green crabs alive. Capt. Marc gave us a link to a site that describes these critters. The crabs from that hatch are the same crab. Those tiny crabs have been eating about three times their body weight EVERY DAY and are growning very fast.

I was so disturbed by my discovery that I took a ride last night to several North shore beaches to see if the crabs were still floating around the Sound. I didn't see any in the water but when I turned over a few rocks, there they were -thousands of them! At EVERY beach I not only found thousands of tiny Japanese Shore crabs but I also found dozens of larger ones. I took a few of the larger specimens home to observe in the tank.

Man, these things are mean looking. They have claws that are so fat that they look like boxing gloves. I also spent a few hours on the internet doing research and found out that they are so powerful that when they see a blue claw crab twice their size, they rip the blue's claws right off of it's body like it was butter. They have huge appetites that consist of everything they could get their claws on including clams, mussels, oysters, scallops, other crabs and possibly baby lobsters! They also eat the macro algea that many of our native species depend upon.

As we saw last month, this species has the ability to reproduce like no other crab we have ever seen in these waters (go back and read the thread under "Crab Bloom". I took some photos of these crabs and will try to have them for you guys shorty. Tonight I am going to put a green crab in the tank next to the Japanese Crabs to see if I can video tape this great power. I think I am also going to write an article for the local newspapers to report my findings. The most depressing part is that when I usually turn over those shore rocks I find a huge variety of species such as fiddler crabs, sand worms, baby eels, grass shrimp, stone crabs, hermit crabs, etc... But it appears that these Japanese Shore Crabs have either eaten all the other species under their rocks or have driven them out with their muscles.

This cannot be good!!!!!

Captain Marc or anyone else, do you know if there is a federal agency or a local group that would be interested in hearing from me about this?

Here are a few links if anyone wants to read about this terrible invader;

Asian Shore Crab

NY Times on Japanese Shore Crab

 

[615953]

Hey Doc,

I was fishing in Mt. Sinai the first time I ever saw the bloom, they came in with the tide in MASS. I had a small gauge net and scooped up at least a couple hundred, threw them in a spare tank with some food. They got huge pretty fast, but they were killed, **** shame I had to hook them for my blackfish, went with 3 crabs per hook, worked out well, just wish I took more to eliminate more of them.

 

[seaslug44]

I've been on the phone with marine bioligists up and down the East coast all morning. I am waiting to hear from one who has a grant to study the effects this crab is having on the marine environment.

Question, how many of you have noticed these small crabs this month or last month in the stomachs of fish you gutted? Let me know they type of fish it was and about how many crabs were in its gut. The bioligists are very eager to prove that local fish are feeding on these crabs.

 

[Johnny B]

I taught a marine science class for children this summer,(I'm not a marine bio or anything I just do it as a serious hobby.) All summer the children were bringing in these crabs and I wasnt exactly sure what they were. They didnt have the chance to grow because the blue claws in the tanks were ripping them apart. Crabs never got bigger than a thumbnail.

 

[Capt. Marc]

DoctorFish,

My first call would be to the DEC at Stony Brook. Did you give them a call and ask for the expert dealing with this problem? Would like to know what they said.

Hopefully this crab isn't so hardy and perhaps a swing in the climate (really cold winter) may keep them in check. Once here it is impossible to get rid of an established invasive species. Our only hope may be that a natural predator may decide they are pretty tasty and become acostomed to eating one stage of development.

Green crabs are an import and I believe they displaced all the blue crabs, I have been told, that once lived in the middle sound area.

This invasion may explode for a few years until nature finds a way to put them in check.

Are the adults edible? A little commercial pressure wouldn't hurt in this case, if so.

Capt. Marc

 

[615953]

Capt. Marc,

I wouldn't bother to eat them, I threw one in with a bunch of blue claws I had, the meat didn't smell good and there wasn't much of it.

DocFish,

In 3 stripers I've kept this year from the sound (26", 30", and 32.5"), I have honestly counted 200, but there was at least 5-10x that amount in there guts. They literally just poured out of the gut. I also have been keeping sea robbins lately, I tried them once and found that they're an easy catch and they're meat is fairly decent... I have found about 500 between 50-60 sea robbins I've kept.

 

[614851]

doctorfish,
i would look to the oyster toadfish (Opsanus tau)to be a major predator, at a wide range of temperatures, on this alien crab.
hey doc, by any chance are you an ocean surgeon?

set,
opinari

 

[seaslug44]

Thanks everyone.

I am like Johnny B, I am not a biologist by trade (there's no money in it) but real serious about it.

Opinari, about 10 years ago I was codfishing near a partyboat that was creating acres of dogfish "floaters". The fish were already dead, but my friends got a real kick out of my ability to do "C-sections" on the female sharks. I am not a surgeon, however, I was able to save about three dozen shark pups.

 

[Hunt n' Fish]

Doc,

I spoke to a DEC biologist at the Setauket office today. He said that the Japanese Shore Crabs have been here for years. They don't get very big, about the size of green crabs.This year they are particularly plentiful but they are not considered a threat to indigenous species at this time. They believe that they are currently a significant source of food for stripers and blackfish.

 

[SOLTA]

NOT JUST THE NORTH SHORE, I HAVE BEEN FINDING THEM IN MY KILLIE POTS THIS YEAR. THEY SEEM TO BE HARDY AND LOOK LIKE GOOD BLACKFISH BAIT.

THANKS ALOT

 

[614851]

doctorfish,

doctorfish (Acanthurus chirurgus) and the ocean surgeon (A. bahianus) are desirable aquarium fish of the tang family, which can be found in our waters. when you mentioned your saltwater aquarium i thought perhaps that was where your name came from.

i am an aquarist also. years ago, while bottomfishing on the captain al, the mate was cleaning a dogfish and out pops 6 pups. i kept them alive in my cooler, brought them home, and put them in a salt water aquarium. i fed them chopped clams, but they were unable to digest it. apparently, their digestive tracts were not sufficiently developed yet. sadly,they perished within a week.

sorry for straying off topic.

set,
opinari

 

[seaslug44]

I was told by several biologists that DEC would respond exactly they way they did to doughboy. Truth is, our dec scientists have not spent ANY money to study this new invasive species. It's amazing that they can talk with such absolutes when they did ZERO research. The real truth is that the science community still does not know enough about this creature and what harm it can do to our environment.

One study indicates that it might be partially responsible for the great lobster decline (are the asian crabs eating lobster hatchlings??). Another study is concerned about how these crabs might threaten the scallop, oyster & clam industries. As Capt Marc mentioned earlier, the entire mid-Sound blue claw crab population was displaced when the Green crab arrived from Europe. The State of Maine was so concerned that they were offering a bounty of $5 per crab. This is serious stuff, but as usual our government is blowing it off.

Wonderful.



This message was edited by DoctorFish on 10-26-01 @ 10:13 AM

 

[fisherking1979]

hey doc,
i have a question? if i buy say 20 eels alive from a bait shop and put the in a salt water tank to try using them for bait next spring for bass and the eels age say 12 inches now how big should the be by the spring? also what if i do the same with peanut bunker? are there still peanuts around?

 

[fisherking1979]

hey doc,
i have a question? if i buy say 20 eels alive from a bait shop and put the in a salt water tank to try using them for bait next spring for bass and the eels age say 12 inches now how big should the be by the spring? also what if i do the same with peanut bunker? are there still peanuts around?

 

[Capt. Marc]

fisherking1979,

Good luck trying to keep 20 eels in a fish tank. You will be lucky to have 1 left by Jan. They will end up under your bed, behide your shoes in the closet or end up under the refrig. Unless you totally secure them from taking nightly excursion out of the tank, they will find a way.

Bunker need lots of plankton and room to live. An aquarium isn't suited for them and the eels will have a field day with them.

Wish I had more positive comments.

Capt. Marc

 

[seaslug44]

Fisherking,

Captain Marc is right. First lets talk about bunker. They are unable to survive in an aquarium with corners because unlike most fish, they do not have any sensors on their snout to make them aware of what is in front of them. Their eye sight has also evolved to be nothing more than a way to detect when a predator is approaching. Take a few and put them in a tank and you'll see what I mean. They crash into the walls and everything else in the tank. I challenge you to find one alive in 24 hours. You can keep the bunker alive in a round "livewell" style tank. However, you are basically just prolonging their death because as Capt Marc mentioned, you will not be able to supply them with live plankton.

When I was still dating my wife, she once met an eel in the hallway leading to my bedroom. As Capt Marc also mentioned, this happens all the time. Even when I thought I had the tank totally sealed and the cover fully weighed down, I had one manage to pull the intake nozzle off of the pump and squirm his way into the filter. As far as growth, eels grow VERY slow. Even with constant feeding, I dounbt you will even notice any change in an eels size over just one winter.

The most important thing you need to consider is that live bait is VERY EXPENSIVE to keep alive. Even just eels alone, if you add up the cost of feeding them to the added electric bill associated with the filer, heater, air pump, etc... you are better off just releasing your leftover eels and buying new ones when the season starts again. Better yet, see if your local tackle store will give you some $$$ credit if you sell them back.

 

[fisherking1979]

thanks for the great info im not even sure if the bass will take eel in the spring when the bunker schools have their attention. your right about the eels also the do get into everything, and the are almost impossible to kill. one night i bought a few put them in a plastic bag threw in the trunk and drove home. (it was cold out) the little water in the bag was ice and so were they. i threw them in the sink with some warm water and there they were alive for another 8 hours for fishing, put them on the hook on a slow night for 2 more hours or so with no luck, unhooked them and released them. they swam off like nothing happen to them. how can the be so resiliant?

 

[seaslug44]

Here is an update on the Asian Shore Crabs...

NYS DEC has basically blown me off. They have taken the position that the crabs have been in the Sound for several years now and it's not a big deal. I've learned this from others who have spoken to them because the shellfish unit hasn't even bothered to return my calls or e-mail messages.

However, the federal government and many private universities/foundations are alarmed. I was asked by a scientist at the National Marine Fisheries/NOAA to preserve a few of the crabs from the September hatch in alcohol and mail it to her. She wants to send them to the Smithsonian Lab for further testing.

I've been asked by a group called the Atlantic Coast Watch to write an article about the intensity of our invasion for their newsletter. I've been in contant contact with many biologists.

I've been warned by almost every biologist I've spoken to that we should all destroy these crabs as soon as we see them. This is consistent with what Capt. Marc advised last month.

There is also a concern about human & marine consumption. There are several questions that have not been addressed such as;

Are these crabs toxic to blackfish, stripers, sea bass, etc...?

Are they carrying any foreign bacteria/infection that could spread to the fish that consume them?

If the crabs do present a toxin or bacterial threat to our marine life, can humans get sick by consuming fish that have been infected?

These are serious concerns/questions that are still unanswered. I hope they prove to be invalid. However, all of us might want to discourage anyone from harvesting these crabs and using them for blackfish bait. In addition, females can carry sperm for extended periods of time. It is possible that using these crabs for bait could help intensify the invasion.

We should wait to hear from the researchers.

I'll keep you all informed.

P.S. -The scallop industry in the Peconics is also very concerned. Their industry has just started on the road to recovery. These crabs are multiplying and they are hungry. Mollusks are a big part of their diet.

 

[Capt. Marc]

DoctorFish,

I would take a trip to the DEC office in Stony Brook with your emails and correspondence in hand and ask to speek to the Department head for the marine science division. Ask him in person why nobody has replied to your attempts to inform then of this problem. Bring in a dead crab as proof.

Whtch them wiggle like a eel!

Thats BS from a public servant.

Keep up the fight.

Capt. Marc
While your there ask them what they are doing about the collapse of the winter flounder fishery.

 

[Gamakatsu]

Capt. Marc,

You mentioned something that makes my blood boil everytime I think about it. They are busy over regulating fluke, porgies and sea bass which all have healthy stocks. Yet winter flounder, ling and whiting are showing signs of collapsing and they do nothing to ease the situation. Why is this????

Gamakatsu