Scientists puzzled by straying mammals

[UM-Bot]

Hooded seals, bottlenose whales and a manatee have been spotted in the waters of the northeastern U.S., leaving marine biologists puzzled as to why they have strayed from their natural habitats. The presence along the Jersey Shore of mammals who normally swim in much warmer or colder waters took a troubling turn recently with the discovery of three of the seals on New Jersey beaches.

All were suffering from starvation or exposure.

View: Full Article | Source: Times Argus

[Reincarnated]

I"m not sure exactly what it is, but it's from human interference and it's sad.

[GreyWeather]

My guess is that we have over-fished in their territory, so they've moved to find a larger variety of prey thatsin more abundance.

[Rag]

While I don't claim to be very informed in the area, could this have anything to do with magnetic forces of the earth at play? I believe I read somewhere that those can cause shifts in migrational activity.

[SeCReT SeRViCe]

iT wouLd SuCk iF iT weRe ReaLLy "uS" ReSpoNsiBle FoR tHe MiGraTioNaL PrObleMs GoiN On, aNoTHeR exaMpLe oF MaN F'iNg EveRyThiNg UpPp...PEACE!!

[Ghost Ship]

Perhaps it's the poles of the Earth shifting towords the great flip of the Earth that's predicted. A cataclysim of ultimate proportions.

Or there looking for there natural diet that's somehow no longer available in there usual habitat.

[Pandora7321]

I was born and live in Jacksonville, Florida. I am VERY surprised that a manatee made it all the way up to New York and beyond. I didn't read the entire article this time, but I didn't see anyone mention it in their replies on here, either. Has anyone suggested global warming? I did read an article a few weeks back that A LOT of animals all over the world are moving their territories due to global warming. They are actually predicting that, while it's possibly good for the animals doing the moving, it may be catastrophic for the animals whose territory these new interlopers are encroaching upon. They said we will be seeing specie interactions that have never been seen before in these times. Who knows what will happen?

[Bella-Angelique]

I thought about climate shift first also.

[QueenOftheCramped]

This might be a possible explanation:

This is a portion of a power point presentation given by Dr. Marsha Green in June 2004 that addresses the impact of high intensity sonar, airguns and shipping on the marine environment. It also addresses International actions being taken concerning this issue.

1. Whales are acoustic animals - They use sound to:

Navigate

Find mates

Find food

Communicate

2. Research shows that whales avoid sounds with a source level of about 120 dB (Richardson et al., 1995, Green et al., 1998)

There are sound sources in the ocean that produce noise levels much higher than 120 dB:

Air guns used for oil exploration & geophysical research (216 - 230 dB) Underwater construction

Explosives

Military sonars Large ships

Acoustic harassment devices

3. These very loud underwater sounds may cause various adverse effects on marine mammals including:

Masking social communications used to find mates or identify predators

Temporary and permanent hearing loss or impairment

Displacement from preferred habitat

Disruption of feeding, breeding, nursing and communication

Strandings

Death and serious injury from hemorrhaging and tissue trauma

4. Public and scientific concern about underwater noise pollution has grown over the last decade after a series of mass mortalities of cetaceans associated with the use of mid-frequency active sonar in coastal areas.

The best documented cases, where stranded animals were recovered in time for necropsy occurred in: Bahamas (2000), Madeira (2000)'

Canary Islands (2002), Bahamas 2000, Canary Islands 2002

5. Cuvier's and other beaked whale species suffered hemorrhaging in:

Brain

Inner ear

Lungs

Eyes

Consistent with injury from intense sound (Fernandez et al 2003 & Jepson et al 2003)

6. Other strandings correlated with the use of naval sonar occurred in:

Greece (1996)

US Virgin Islands (1998,1999)

Canary Islands (1985, 1986, 1989)

NW Coast of US (2003)

However, the magnitude of the problem is not known since recent evidence indicates whales may die at sea where carcasses sink and are almost impossible to detect.

7. Are Current "Safe" Exposure Levels Really Safe?

It now appears that at least some of the injured whales in the Bahamas stranding were exposed to sound levels of 160-165 dB

In their Environmental Impact Statement the Navy extrapolated that the safe exposure level for marine mammals is 180 dB

8. High intensity sonar has been shown to have adverse impacts on other marine species as well.

9. The British Defense Research Agency reports that fish exposed to Low Frequency Active Sonar above 160 dB suffered:

Internal injuries

Eye hemorrhaging

Auditory damage

Fifty-seven percent of brown trout died after exposure to levels above 170 dB.

10. Air Guns:

Air guns (216 - 230 dB) can also cause marine mammal strandings and affect fish

Used to find and monitor oil reserves

Often operate for long periods of time

Fire every few seconds

Norway's Institute of Marine Research found that trawl catch rates of haddock and cod fell 45 - 70% over a 5,000 square kilometer area when air guns were being used.

Catch rates did not increase for the five days surveyed after air guns stopped.

Many species show active avoidance at 3-20 km

Blue whales stopped vocalizing for 1 hour at 10 km distance

Sperm whales stopped vocalizing for 36 hours at 370 km distance

Sperm whale distribution has been observed to change in response to seismic operations in the Gulf of Mexico

Two beaked whales stranded in the Gulf of California in September 2002, one hour after a research vessel using air guns was 22 km away

Whales stranded in the Galapagos Islands while the same research vessel was operating in the area (2000)

11. Shipping:

The main source of noise is the ship's propeller which produces a loud hiss that dominates the low frequencies below 600 Hz in heavy shipping areas

The leading noise producers are oil tankers and bulk dry ships

Icebreakers cause avoidance reactions in narwhales, belugas, walruses

Some whales rely on low-frequency sound for communication over vast distances

These are the same frequencies occupied by vessel noise

Some scientists are concerned that shipping could have population - level impacts on these species

One scientist reported that 1/3 of all stranded cetaceans they necropsied had some form of auditory damage

High Intensity Active Sonar Update (2003)

Source

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The US Navy and other navies are planning to operate potentially lethal high-intensity active sonars, including Low Frequency Active Sonar (LFAS) in 75% of the world's oceans. LFAS has never been officially tested at exposure levels above 155 dB which is about one-millionth the intensity of the proposed deployment source level. Recent disclosures indicate that the scope and risks of harm from LFAS are broader and more serious than previously understood. "The full scope of evidence regarding impacts on marine mammals (including a growing number of mass strandings) at exposure levels far below the proposed 180 dB injury threshold, and the serious risks that LFAS poses to fish and human divers have become public only within the last year" (Amended Plaintiff's Motion for Summary Judgment Case Number CO2-3805 EWL, USA). According to the US Navy, signals from LFAS can still be 120 dB, a sound level causing avoidance behavior in whales, up to 1,111 km away from the deploying vessel. Since the sounds spread in all directions the signal from one vessel ensonifies a very large area of the ocean.

Marine Mammals

Necropsy reports show that injuries from mid-frequency sonars have caused whales to strand and die most notably in the Bahamas (2000) and the Canary Islands (2002). In fact, mid-frequency sonar appears to have devastated the Bahamas beaked whale stock as a whole. Most recently, other incidents of cetacean strandings or deaths coincident with naval exercises have been discovered including: Vieques, 1998 & 2002; Madeira, 2000; US Virgin Islands, 1999; Greece, 1996; the Canary Islands 1985, 1986, 1988, 1989 and the northwest coast of the US (2003). While the effect on marine mammals is more serious than previously thought, the extent of the problem is not known since both low and mid-frequency sonars and low frequency seismic air guns have been implicated. Evidence indicates that not all seriously injured animals strand; some die at sea, sink and are usually not discovered.

Source

___________________________________________________

Edited October 2, 2006 by QueenOftheCramped