长鳍鲭鲨（学名Isurus paucus），又名长臂灰鲭鲨，是鼠鲨科中大型的鲨鱼，分布在温带及热带的海域。牠们一般被称为马加鲨，「马加」是其英文名的「mako」的译音。

长鳍鲭鲨可长成超过4米长，背部呈深蓝色，腹部呈白色。胸鳍与头部一样，或甚至更长，鳍身较阔。鼻尖较钝，一般都不甚尖锐。上下颚的牙齿笔直。尾鳍呈半月型，有非常长及低的突出位。牠们一般都是较幼身的，阔的胸鳍代表牠们游得比其近亲的尖吻鲭鲨较慢。

长鳍鲭鲨的阵速可以超过每小时60里，并且可以跃起至6米高。

长鳍鲭鲨是卵胎生的，妊娠期约为15-18个月。在长鳍鲭鲨母体内的胚胎会互相消耗对方来取得养份，每胎只有两头幼鲨出生，这是子宫内同类相食。

The longfin mako shark (Isurus paucus) is a species of mackerel shark in the family Lamnidae, with a probable worldwide distribution in temperate and tropical waters. An uncommon species, it is typically lumped together under the name "mako" with its better-known relative, the shortfin mako shark (I. oxyrinchus). The longfin mako is a pelagic species found in moderately deep water, having been reported to a depth of 220 m (720 ft). Growing to a maximum length of 4.3 m (14 ft), the slimmer build and long, broad pectoral fins of this shark suggest that it is a slower and less active swimmer than the shortfin mako.