Posts
Sea Lamprey and the Unexpected Costs of Shipping
Sea Lamprey accessed the upper Great Lakes when shipping access was improved. They arrived at a time when Walleye, Lake Trout, Burbot, and Whitefishes were commercially over harvested. The added mortality from Sea Lamprey was the tipping point that led to collapse of these valuable fisheries. Expensive control efforts continue to the present time to deal with this invader.
 |
| Oral disc of the parasitic Sea Lamprey. Photo by Cory Genovese |
Gray Snapper are common on Caribbean reefs that attract large spawning aggregations. They go by a variety of names because they do not always appear to be "gray." Gray Snapper are often overfished. This story of the habitat and life history of Gray Snapper emphasizes the importance of conserving both inshore seagrass and mangrove habitats as well as offshore coral reefs.
 |
| Gray Snapper. Photo by Ned DeLoach Source |
This story explores how super abundant shark aggregations in a biosphere reserve persist because they rely on spawning aggregations of groupers for energy subsidies. This discovery illustrates the futility of single species fisheries management. Even if no sharks were harvested from this population, the population may decline depending on conditions for other fishes outside the biosphere reserve. Conservation of fish spawning aggregations, which are often targets of exploitation can help conserve shark populations, especially if combined with shark fishing bans.
 |
| Examples of shark foraging at night on the Camouflage Grouper Epinephelus polyphekadion (A, B, and C) and the Whitemargin Unicorn fish Naso annulatus (D). Source |
The Pike Killifish is an enigma. It is the only member of the Poeciliidae family that is a specialized piscivore. Pike Killifish live in slow-moving streams and rivers, mangrove and weedy swamps, and inlets salty bays, where they associate with abundant submersed vegetation. Their native distribution ranges from Costa Rico north into parts of Mexico. From a single introduction in Miami-Dade County in 1957, the Pike Killifish became established in south Florida where their wide tolerance for temperature, salinity, and oxygen level allowed them to thrive in many habitats.
 |
| Large adult Pike Killifish. Photo by Kenneth Tse Photography |
Madtoms are diminuitive catfishes that are bound to intrigue those who encounter them. However, their pectoral and dorsal fin spines are sharp and deliver a painful venom. Madtoms have a paradoxical combination of the strong anti predator adaptation while being a very popular bait fish.
 |
| How cute is this Margined Madtom Noturus insignis? Be careful, it packs a painful sting. Photo by D.J. Orth. |
These benthic nocturnal catfish arose in eastern North America sometime in the middle Miocene (that's 23.03 to 5.33 million years before the present). Many of the twenty nine species have small, fragmented populations and are at-risk from a variety of human activities. Although they are seldom the subject of thorough population studies, restoration activities are more commonplace today. Madtom species are cryptic in more ways than one. Click here to review some madtom photos.
 |
| Mountain Madtom Noturus eleutherus have a highly fragmented distribution. photo by Tim Lane |
In this essay, Rasha Aridi explains how shark offspring can be produced without a male contribution. In 2002 a bonnethead shark gave birth in a zoo even though it had never been kept with a male. This "virgin shark" mystery persisted and keen observers began to investigate cases of virgin birth in captivity. Using DNA fingerprinting, these cases confirmed that all elements of the DNA in the offspring were from the mother. Some species of sharks can produce offspring via sexual reproduction and parthenogenesis.
 |
| Parthenogenic zebra shark pup hatched and reared by the Burj Al Arab Aquarium Team. Source. |
A major typhoon devasted an island resort leaving little or no infrastructure. This essay examines the response of the locals in building a tourism-based economy based on the Thresher Shark. Fisherman who used to make their money from catching as many thresher sharks as they could now make their money from this unique eco-tourism trade.
 |
| Thresher Shark. Photo by Hugh Ross. Source |
Siberian Taimen: Ensuring the Survival of the River Wolf, by Spencer Bell
Hucho taimen is known to the Chinese as the "river god's daughter." Mongolians protected their rivers for many centuries in keeping with their beliefs. Consequently, some populations of the largest salmonid in the world still remain. Today, recreational catch-and-release fishing has replaced poaching on the remaining Taimen populations.
 |
| Three Taimen, underwater photo from Eg River, northern Mongolia. Source. |
Bow fishing for "Rough" Fish
Rough fish is an old term that once referred to less valued fish that had yet to be processed. Today, more anglers are targeting rough fish for sport and bow fishing is among the fastest growing new fishing pursuits. However, fishing regulations must change with the time and the term "rough" fish need to be replaced with more appropriate language.
 |
| Bow fishing at dusk. Photo by Jason Emmel |
Climate Change and the Fishes
Fear and doom stories about climate change have led to more research and development of strategies for adapting to eventual changes. However, the scientific investigations have revealed a complex interactions of stressors related to climate change. Although there is still much to learn, it is apparent that we need to act now to protect cole and cool water refugia.
 |
| Documented responses of fishes in the southeastern USA to climate change. Green arrows indicate an increase or earlier seasonal response, and gray arrows indicate a decrease or later seasonal response (Lynch et al. 2016). |
In my home watershed there are 8 species of endemic fishes. They are all cool water specialists that found refuge in the upper New River during the last ice age. These endemic fishes have limited distributions and will be disproportionately influenced by anthropogenic changes that may occur. Read more about these 8 species in this post to learn why the New River is a special place for fishes.
 |
| New River near Rich Creek, Virginia. Photo by Valerie F. Orth. |
How many dams are there in the USA? How many dams have been removed from streams? What happens to the stream after dam removal? What are the gaps in the science of dam removal? Learn the answers to these and other questions.
 |
| Pigg River Power Dam before (photo by USFWS) and during demolition (photo by Roanoke Times) |
No comments:
Post a Comment