What do you do to protect yourself if you are a yummy, and yet vulnerable, soft-bodied octopus roaming around the open sea floor? You become a master of disguise. It is well known that octopuses are surprisingly intelligent and have an impressive knack for camouflaging their skin to match their surroundings. In recent years, however, scientists have begun to recognize that the octopus can take this a step further by mimicking other animals, algae or inanimate objects.
Recently, researcher Roger Hanlon and his co-authors from the Marine Biological Laboratory in Woods Hole, Massachusetts, have discovered that the sand-dwelling octopus Macrotritopus defilippi can mimic the swimming behavior and coloration of a common flatfish species. In this video an octopus swims with its body against the sea floor and it’s legs trailing behind.
In 2005, Christine Huffard and co-authors, from the University of California, Berkeley and Universitas Sam Ratulangi, Indonesia, found that an octopus species in Indonesia (Octopus marginatus) can ‘walk’ on two legs to mimic a coconut.
Apparently, it is not uncommon to find coconuts rolling on the seafloor in the region. In addition, the same team observed octopuses of the species Octopus aculeatuswalking like floating algae in Australia.
Much like Chinook salmon stock abundance that has been variable up and down the West Coast over the last few years, this years hatchery steelhead returns are down in California’s Central Valley, but up at coastal tributary hatcheries.
Recent counts at the Nimbus Fish Hatchery on the American River are 92% of last year, or 1,004 steelhead. The Feather River Hatchery reports just 85 steelhead returning, 30% of last year, and the Mokelumne River Hatchery has seen only 31% of lasts year’s count, or 160 fish.
California coastal tributaries are faring better for steelhead this year than the Central Valley. The Warm Springs and Coyote Valley Hatcheries in the Russian River Basin are up 265% and 292%, respectively. Further up the coast Mad River Hatchery steelhead returns are up 487%, or 1,372 fish this year compared to 282 last year. Interestingly, the Trinity River Hatchery is 181% for the same time period last year, whereas Iron Gate Hatchery on the Klamath River is lower than last year, with only 21% of last years abundance.
Over the years we have learned not to be surprised at the things we catch in our various traps and sampling techniques, but the animals we catch do not have the benefit of our experience, and are usually quite perplexed at their current predicament.
Such is the case with this muskrat (Ondatra zibethicusis ) looking up at us from the inside of a large dip-net. Muskrats are a medium-sized semi-aquatic rodent native to North America commonly found in lower elevation rivers and wetlands. Muskrats are well adapted for aquatic life with partially webbed feet, laterally flattened tail and dense fur. They only grow to about 2 feet with half of that being tail, feed on cattails and other aquatic vegetation, and do not store food for the winter.
Largemouth bass have two ecologically distinct life-stages. They begin life feeding on invertebrates and typically switch to preying on fish within one year of age. Research has shown that once largemouth bass become piscivorous their growth rate increases, giving them a size advantage over other fish the same age.
What’s more surprising than an albino ratfish? How about the fact that ratfish (Hydrolagus colliei) are the most abundant fish in Washington’s Puget Sound! As recently as 2005 the Washington Department of Fish and Wildlife estimated their biomass at 170 million pounds, 5 times greater than herring, the next most abundant fish.
Although the albino sailfish recently captured in Cabo was a good example of a fish defying the odds, this one may be better. Whereas the typical ratfish is brown/black with spots to help it blend into the bottom, this fish was completely white and was even described with a “crystalline layer” that gave it a silvery sheen. In other words, it was constantly asking to be eaten.
Ironically, its albinism did ultimately lead to its demise, only by curious researcher rather than hungry predator.
Fish biologists mark fish with a variety of techniques, but always with the same goal of being able to identify previously captured fish, usually for the purpose of estimating the size of a population or efficiency of a capture technique.
This Chinook salmon fry was just marked by injecting a photonic dye into its caudal fin. Although it looks extreme, very little dye is actually injected into the fin tissue, leaving only a small mark that can be seen with careful examination of the fish. The dye is temporary and experiments have shown that it does not substantially affect fish health or survival.
Costa Rica is a beautiful Central American country with important marine commercial and sport fisheries. The majority of commercial fisheries are located on the Pacific side of the country, and consist of tuna, shimp, sardine, kingfish, and snapper. Although the economic value of commercial fisheries is low compared to larger countries, it is important to a small country like Costa Rica with only about 4 million people. In 2002 the fishery and aquaculture sector contributed 0.32% of the GDP (FAO 2004, does not include sport fish).
Sport fishing off the Pacific coast has increased dramatically within the last few years, and fishing for blue marlin and Pacific sailfish in the southern Pacific zone is now widely regarded as some of the best in the world. In 2002 the United Nations Food and Agriculture Organization estimated the value of the sport fishing industry at around $32 million USD, and it has grown substantially since then. The stocks involved in sport fishing are likely impacted by commercial longline fleets, and some commercial restrictions have been put in place (FAO 2004). In addition to open water fishing for marlin, sailfish, wahoo, and tuna, nearshore and estuary species like snook, tarpon, and barracuda are very popular game fish. Sport fishing for rainbow trout that were introduced from U.S. stocks in the 1970’s also takes place in upland areas with cool streams.
This conjoined twin (polyembryonic) chinook salmon fry was recently caught in a downstream migrant trap. Though we occasionally see fish like this, they are relatively rare and we have not observed them in the wild at sizes any larger than 50 millimeters. Their rarity is likely a result of their high susceptibility to predation because of reduced swimming performance, similar to the fish in our “Not all fish are created equal” post.
