This week we have a piece written by a pair of Mass Maritime Academy students who are spending their winter break with us. Cadet Michael Kerrigan is a Junior at the Academy and is fulfilling his co-op requirement here at the Landing. Cadet Holly McLaughlin is a freshman who is volunteering to help us out.
Enjoy...
Many rivers and streams are nurseries to different juvenile fish. The reason for this is because they provide protection from predators and provide ideal spawning grounds. Some of these areas can be strictly salt or fresh water flowing, but some are a mixture of both. These areas are commonly known as estuaries. An estuary is a transition zone from where freshwater flows to seawater. This prevents predators from going up these types of rivers and streams because their bodies can't handle the transition of salinity. These types of rivers are very significant because problems continue to grow along them and affect wildlife, specifically populations of spawning fish such as river herring.
River herring are migratory fish that travel in various amounts known as schools. There are normally two fish species linked together when using the term river herring, Alewife (Alosa psuedoharengus) and Blueback herring (Alosa aestivalis). Alewives can live up to 10 years, grow as large as 36cm, and spawn in early spring when water temperatures are between 60F (16C) and 66F (19C). While blueback herring live up to 8 years, grow up to 40cm, and spawn a little later than Alewives in spring when water temperatures are between 70F (21 C) and 75F (24C) .They are both also anadromous fish, which means they are one of the many types of fish that travel up rivers or streams to spawn and then travel out to sea. Although this process seems fairly simple, in some cases it isn't. River herring face many obstacles between the ocean and their spawning grounds causing a continual decline in population .Most herring return to their natal spawning ground, but due to various human activity, they can not reach their destination. This includes, but is not limited to the water quality of the area, over fishing and bycatches, and loss of habitat. All of these factors can be related to anyone living on or near a river.
There are many contributions that can cause a decline in water quality. Along rivers there are recreational activities, houses, and businesses, which all effect the condition of the water. Among some of the recreational activities are boaters, which can be seen as a contributor to water pollution. A lot of boating activity in an area constitutes a problem as well because the river is faced with constant engine idling, harmful bilge pump outs, and oil or gas spills and leaks. Also, many boaters have small portable toilet systems and do not take the proper measures to go to a pump out station as directed. Instead many pump them directly overboard with no treatment leaving sewerage in the area. Houses along the river can be a cause of sewerage infiltrating the river as well. Many of the houses in the area have septic systems with leaching fields. Leaching field discharge often finds its way to bodies of water. Also, when the river has high tides it can flood septic systems and pull back pollution as the tide retreats. Even with homes that had septic systems that have recently connected to the sewerage line can still pose problems. This is because although the system isn't geting anything put into it the leaching fields are still discharging and the soils around them take time to be flushed out. Also, homes around the river have sediment runoff into it. All runoff is, is when it rains or water is applied to a surface it will find low points normally leading to a river or stream and carry material with and substances with it. With homes this can cause problems because many people apply lawn fertilizer, pesticides, and have fluids leaking out of there cars. All of these substances can eventually make there way through runoff to a stream or river. Some businesses produce water pollution as well because they are allowed to discharge small amounts into rivers causing further contamination. All of these factors contribute to water quality. The fish cannot return in order to spawn if the water is not clean enough.
River herring are an easy species to be targeted as bycatch. This is because they travel in schools that can be made up of large numbers. As they move closer to there spawning grounds they become more confined as the river narrows, making them an easier target for fishermen. Besides just river herring which go upstream to spawn, there is also the Atlantic Herring (Clupea Harengus) which are strictly marine fish which have some restrictions on harvesting but not a total closure to the fishery. This is where most of the bycatch takes place and the fish are taken. River Herring have harvesting bans which restrict fishermen from catching them. River Herring populations have been drastically decreasing. For example, fishery landings have declined from 40,000 tons in the 1950s to less than 3,500 tons in 2005 (FAO, 2007). This is why rather than being a targeted species, they are often bycatch, getting caught in gear such as gillnets and midwater trawls.
In the early 1900's, as industry grew, the more people harvested hydro power off of rivers for convenience in factories. With many of these factories gone, still standing dams are left behind. This interrupts the natural flow of the river as well as the habitat of everything that lives in or around the area. Dams make it impossible for the herring to migrate back to their original spawning grounds. Although some actions have been taken to allow fish to pass, there is still no solution to the problem. Fish ladders are one of the solutions, but they do not solve the problem because fish can be too weak to swim up or locate them. If fish ladders are present and hydro power is being generated, they still pose a threat for many reasons. Herring are a velocity species, which will cause them to swim closer to the turbines. As they get closer to the turbines, they will be in the tail race where over oxidization of the water occurs. The herring may also swim up into the
turbine discharge tube, which will either kill them or lead them to a dead end. Some actions put into place are installing metal screens, so the fish don't have access to these areas, but they are not very reliable.
The obstacles that the river herring population face can be prevented. Many of these problems can be addressed with simple procedures. For instance, in boating aspects, funnels can be used to avoid spillage, safer chemicals can be used when cleaning, and catching bilge water while discharging can be helpful. To address the septic system problems, connecting to the town sewerage would be ideal. When doing any yard work or maintenance be cautious of any harmful chemicals used or put down and also check your cars periodically for leaks or drips that could be going onto the ground. Although the cost is high, dam removal would be an great solution for dams that are nonfunctional. Most obstacles river herring face can be eased and if we all do our part we can help rebuild their population.
Wednesday, February 10, 2010
Friday, January 29, 2010
Don't be fooled
What a difference a day makes. At this time of year it's more apparent than ever. We've had a stretch of warm weather and although we knew better many of us were thinking spring. But the reality is that water temperatures are down near the 30 mark and it only takes a bit of cold air to freeze us in again.
Tuesday, January 19, 2010
Sand Tiger Sharks.
Our annual meeting will be held on January 24, 2010. One of the featured speakers will be Jeff Kneebone of Division of Marine Fisheries. Jeff will be discussing his current PhD research on Sand Tiger Sharks. To pique your interest and give you a bit of background, I'm reposting a DMF summary of the project. This was was originally prepared by DMF in 2008 and featured on our website....
The sand tiger shark (Carcharias taurus) is a large coastal species that ranges from the Gulf of Maine south to the Gulf of Mexico along the east coast of the United States. They are commonly found in inshore waters ranging from 6 – 600 feet in habitats such as surf zones, shallow bays and estuaries, rocky and coral reefs and near shipwrecks. Sand tigers can be identified by the presence of two large dorsal fins, a large anal fin, large thin teeth, dusky spots along the side of the animal and black coloration at the tips of the fins.
Sand tiger sharks in New England:
Sand tiger sharks are seasonal visitors to New England waters during the warmer months of June – November. In the early to mid 1900’s sand tiger sharks were considered to be one of the most common shark species in New England waters and both commercial and recreational fishermen caught large numbers of individuals as far north as southern Cape Cod Bay. During this time, a directed commercial fishery was established in Nantucket Shoals, however, this fishery was short lived due to rapid depletion of the local stock. Unfortunately, increased fishing pressure on the species along the entire east coast of the United States during the mid – late 1900’s severely depleted sand tiger populations, including those around New England. In 1997 as a precaution to stop fishing mortality, the National Marine Fisheries Service (NMFS) prohibited sand tiger sharks from being targeted and retained in both commercial and recreational fisheries. In 2005, Massachusetts state law also prohibited the targeting and retention of sand tiger sharks in state waters.
During the last few years, an increasing number of juvenile sand tiger sharks are being incidentally caught in Massachusetts coastal waters, particularly along the south shore in Plymouth, Kingston, Duxbury (PKD) Bay. Interestingly, occurrence of sand tiger sharks in this region appears to be a relatively new phenomenon as local fishermen claim they have never seen this species in this region until recent years.
Our Research:
Over the last few years the Massachusetts Shark Research Program (MSRP) has worked with commercial and recreational fishermen in the region to investigate the presence and abundance of sand tiger sharks in Massachusetts state waters. Based on recent catch records, most of the sharks inhabiting the region are young of the year (newborn) individuals. While the lack of large females in Massachusetts precludes the use of Plymouth, Kingston, Duxbury Bay for parturition (birth), it appears as though these coastal waters provide secondary nursery habitat for sand tigers that move north from southeastern pupping grounds. Given their increasing numbers in PKD Bay, this embayment may be the most important secondary nursery area for this species north of Delaware Bay.
At present, the MSRP has a study underway goaled at investigating regional movement, habitat use and the effects of capture of sand tiger sharks inhabiting New England coastal waters. Working in conjunction with local commercial and recreational fishermen, the MSRP is actively tagging sand tiger sharks with acoustic telemetry tags to quantify both regional and large-scale movement patterns and habitat use. Each acoustic tag emits a unique coded signal that can be picked up by a series of underwater receivers (listening stations) located in fixed positions within Plymouth, Kingston, Duxbury Bay and Massachusetts coastal waters. If a shark swims within range of a receiver, the unique signal of its acoustic tag will be logged and stored as a data point on the receiver. Periodically the data logged by the receivers will be downloaded onto a computer and analyzed to generate information on regional movement, habitat use and overall ecology. Fortunately, receiver arrays maintained by other researchers in other regions (i.e. Delaware Bay and North Carolina) are capable of detecting fish tagged in New England waters, allowing for the potential to learn about large-scale movements of these young fish.
Data to date
In September 2008, three sand tigers were tagged with acoustic tags within PKD Bay. In the few weeks during which they remained in the Bay, various receivers logged 2,727 detections and provided some interesting information about habitat utilization. Interestingly, one fish tagged in the Jones River in early September was detected in a receiver array near the entrance to Pamlico Sound (Cape Hatteras, North Carolina) during mid-January.
During the 2009 season, the MSRP will continue tagging sand tiger sharks with acoustic transmitters within PKD Bay. Working in conjunction with the Jones River Environmental Heritage Center, the MSRP also hopes to periodically maintain captive sand tiger sharks in a holding tank located at the Jones River Landing for experimental purposes as well as for public outreach.
If you would like more information about this project or would like to report information about sand tiger shark occurrence in Massachusetts waters, please contact the Massachusetts Shark Research Program at 508-910-6329 or 508-693-4372.
References
Bigelow, H. B. and W. C. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin of the
Fish and Wildlife Service. 53:74
Gilmore, R.G., J.W. Dodrill, and P.A. Linley. 1983. Embryonic development of the sand tiger
shark Odontaspis taurus (Rafinesque). Fishery Bulletin 81:201-225.
Skomal, G.B. 2007. Shark nursery areas in the coastal waters of Massachusetts. American
Fisheries Society Symposium 50:17-33.
The sand tiger shark (Carcharias taurus) is a large coastal species that ranges from the Gulf of Maine south to the Gulf of Mexico along the east coast of the United States. They are commonly found in inshore waters ranging from 6 – 600 feet in habitats such as surf zones, shallow bays and estuaries, rocky and coral reefs and near shipwrecks. Sand tigers can be identified by the presence of two large dorsal fins, a large anal fin, large thin teeth, dusky spots along the side of the animal and black coloration at the tips of the fins.
Sand tiger sharks in New England:
Sand tiger sharks are seasonal visitors to New England waters during the warmer months of June – November. In the early to mid 1900’s sand tiger sharks were considered to be one of the most common shark species in New England waters and both commercial and recreational fishermen caught large numbers of individuals as far north as southern Cape Cod Bay. During this time, a directed commercial fishery was established in Nantucket Shoals, however, this fishery was short lived due to rapid depletion of the local stock. Unfortunately, increased fishing pressure on the species along the entire east coast of the United States during the mid – late 1900’s severely depleted sand tiger populations, including those around New England. In 1997 as a precaution to stop fishing mortality, the National Marine Fisheries Service (NMFS) prohibited sand tiger sharks from being targeted and retained in both commercial and recreational fisheries. In 2005, Massachusetts state law also prohibited the targeting and retention of sand tiger sharks in state waters.
During the last few years, an increasing number of juvenile sand tiger sharks are being incidentally caught in Massachusetts coastal waters, particularly along the south shore in Plymouth, Kingston, Duxbury (PKD) Bay. Interestingly, occurrence of sand tiger sharks in this region appears to be a relatively new phenomenon as local fishermen claim they have never seen this species in this region until recent years.
Our Research:
Over the last few years the Massachusetts Shark Research Program (MSRP) has worked with commercial and recreational fishermen in the region to investigate the presence and abundance of sand tiger sharks in Massachusetts state waters. Based on recent catch records, most of the sharks inhabiting the region are young of the year (newborn) individuals. While the lack of large females in Massachusetts precludes the use of Plymouth, Kingston, Duxbury Bay for parturition (birth), it appears as though these coastal waters provide secondary nursery habitat for sand tigers that move north from southeastern pupping grounds. Given their increasing numbers in PKD Bay, this embayment may be the most important secondary nursery area for this species north of Delaware Bay.
At present, the MSRP has a study underway goaled at investigating regional movement, habitat use and the effects of capture of sand tiger sharks inhabiting New England coastal waters. Working in conjunction with local commercial and recreational fishermen, the MSRP is actively tagging sand tiger sharks with acoustic telemetry tags to quantify both regional and large-scale movement patterns and habitat use. Each acoustic tag emits a unique coded signal that can be picked up by a series of underwater receivers (listening stations) located in fixed positions within Plymouth, Kingston, Duxbury Bay and Massachusetts coastal waters. If a shark swims within range of a receiver, the unique signal of its acoustic tag will be logged and stored as a data point on the receiver. Periodically the data logged by the receivers will be downloaded onto a computer and analyzed to generate information on regional movement, habitat use and overall ecology. Fortunately, receiver arrays maintained by other researchers in other regions (i.e. Delaware Bay and North Carolina) are capable of detecting fish tagged in New England waters, allowing for the potential to learn about large-scale movements of these young fish.
Data to date
In September 2008, three sand tigers were tagged with acoustic tags within PKD Bay. In the few weeks during which they remained in the Bay, various receivers logged 2,727 detections and provided some interesting information about habitat utilization. Interestingly, one fish tagged in the Jones River in early September was detected in a receiver array near the entrance to Pamlico Sound (Cape Hatteras, North Carolina) during mid-January.
During the 2009 season, the MSRP will continue tagging sand tiger sharks with acoustic transmitters within PKD Bay. Working in conjunction with the Jones River Environmental Heritage Center, the MSRP also hopes to periodically maintain captive sand tiger sharks in a holding tank located at the Jones River Landing for experimental purposes as well as for public outreach.
If you would like more information about this project or would like to report information about sand tiger shark occurrence in Massachusetts waters, please contact the Massachusetts Shark Research Program at 508-910-6329 or 508-693-4372.
References
Bigelow, H. B. and W. C. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin of the
Fish and Wildlife Service. 53:74
Gilmore, R.G., J.W. Dodrill, and P.A. Linley. 1983. Embryonic development of the sand tiger
shark Odontaspis taurus (Rafinesque). Fishery Bulletin 81:201-225.
Skomal, G.B. 2007. Shark nursery areas in the coastal waters of Massachusetts. American
Fisheries Society Symposium 50:17-33.
Subscribe to:
Posts (Atom)