According to the National Oceanic and Atmospheric Administration at least 11 dolphins were discovered mutilated along the Texas Gulf Coast over the last eight years, the Houston Chronicle reported on Saturday.
One of those cases saw a dolphin shot and its head cut off, while an additional 31 were injured or killed by boats and fishing gear.
"We are very concerned that people are injuring and killing and hurting these dolphins," Erin Fougeres, stranding program coordinator for NOAA's southeast region, told the Chronicle.
Fougeres said evidence that human harm to dolphins is increasing is anecdotal. But she also believes there are more cases because of increased dolphin interaction with people, and she indicated that dolphins have been found stranded on Gulf beaches by marine mammal stranding networks.
Some were discovered with parts of their bodies lopped off or slashed with knives, Fougeres said.
Fougeres said cases have been recorded all along the Gulf Coast, from Florida to Texas. But Texas' most recent incident came on March 12 when a dolphin was discovered on Crystal Beach with a long cut down its abdomen that allowed its organs to spill out.
Another dolphin was found Feb. 8 on North Padre Island with its head severed.
In Mississippi last month, a dolphin was found after being shot, the third in that state this year. In Louisiana, meanwhile, two dolphins slain by gunfire were discovered this year and last.
The newspaper said no dolphins killed by gunshots have been recorded in Texas since June 2007, when a dead dolphin was found floating in Corpus Christi Bay with a bullet wound. Its head had been sliced off, according to records reviewed by the Chronicle.
In Alabama, a dolphin was found this summer with a screwdriver stuck in its head. Another was found with its tail cut off.
Fougeres said dolphins are sometimes mutilated after death. A passerby may find a dead dolphin and cut off a piece for a souvenir. And, bullet wounds could come from someone using a dead dolphin that washed up on the beach for target practice.
Fougeres said commercial anglers sometimes cut up dolphins that have become entangled in their nets, but that many will cut their gear instead. Fishermen sometimes shoot at dolphins to keep them from disturbing their bait.
Officials reported 31 cases of dolphin injuries involving boats and fishing, including eight who died after being involved in a boat collision, and 23 dolphins how were stranded alive or deceased due to fishing gear or other gear entanglement, Fougeres said.
An NOAA spokeswoman said more than 60 human interactions with dolphins were recorded in 2010, the latest data available, although not all of those interactions resulted in harm to the animals.
Fougeres said even those who interact with dolphins in a friendly way can harm them, such as by feeding the animals and teaching them to approach boats that can later have dire consequences.
Fougeres said it is illegal to feed or touch dolphins and illegal to remove dolphin parts. Harming dolphins or removing their parts are punishable by a fine of up to $100,000 and a year in jail for each violation.